diff --git a/third_party/libxml/src/triodef.h b/third_party/libxml/src/triodef.h
new file mode 100644
index 0000000..fa89416
--- /dev/null
+++ b/third_party/libxml/src/triodef.h
@@ -0,0 +1,222 @@
+/*************************************************************************
+ *
+ * $Id$
+ *
+ * Copyright (C) 2001 Bjorn Reese <breese@users.sourceforge.net>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+ * MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE AUTHORS AND
+ * CONTRIBUTORS ACCEPT NO RESPONSIBILITY IN ANY CONCEIVABLE MANNER.
+ *
+ ************************************************************************/
+
+#ifndef TRIO_TRIODEF_H
+#define TRIO_TRIODEF_H
+
+/*************************************************************************
+ * Platform and compiler support detection
+ */
+#if defined(__GNUC__)
+# define TRIO_COMPILER_GCC
+#elif defined(__SUNPRO_C)
+# define TRIO_COMPILER_SUNPRO
+#elif defined(__SUNPRO_CC)
+# define TRIO_COMPILER_SUNPRO
+# define __SUNPRO_C __SUNPRO_CC
+#elif defined(__xlC__) || defined(__IBMC__) || defined(__IBMCPP__)
+# define TRIO_COMPILER_XLC
+#elif defined(_AIX) && !defined(__GNUC__)
+# define TRIO_COMPILER_XLC /* Workaround for old xlc */
+#elif defined(__DECC) || defined(__DECCXX)
+# define TRIO_COMPILER_DECC
+#elif defined(__osf__) && defined(__LANGUAGE_C__)
+# define TRIO_COMPILER_DECC /* Workaround for old DEC C compilers */
+#elif defined(_MSC_VER)
+# define TRIO_COMPILER_MSVC
+#elif defined(__BORLANDC__)
+# define TRIO_COMPILER_BCB
+#endif
+
+#if defined(VMS) || defined(__VMS)
+/*
+ * VMS is placed first to avoid identifying the platform as Unix
+ * based on the DECC compiler later on.
+ */
+# define TRIO_PLATFORM_VMS
+#elif defined(unix) || defined(__unix) || defined(__unix__)
+# define TRIO_PLATFORM_UNIX
+#elif defined(TRIO_COMPILER_XLC) || defined(_AIX)
+# define TRIO_PLATFORM_UNIX
+#elif defined(TRIO_COMPILER_DECC) || defined(__osf___)
+# define TRIO_PLATFORM_UNIX
+#elif defined(__NetBSD__)
+# define TRIO_PLATFORM_UNIX
+#elif defined(__Lynx__)
+# define TRIO_PLATFORM_UNIX
+#elif defined(__QNX__)
+# define TRIO_PLATFORM_UNIX
+# define TRIO_PLATFORM_QNX
+#elif defined(__CYGWIN__)
+# define TRIO_PLATFORM_UNIX
+#elif defined(AMIGA) && defined(TRIO_COMPILER_GCC)
+# define TRIO_PLATFORM_UNIX
+#elif defined(TRIO_COMPILER_MSVC) || defined(WIN32) || defined(_WIN32)
+# define TRIO_PLATFORM_WIN32
+#elif defined(mpeix) || defined(__mpexl)
+# define TRIO_PLATFORM_MPEIX
+#endif
+
+#if defined(_AIX)
+# define TRIO_PLATFORM_AIX
+#elif defined(__hpux)
+# define TRIO_PLATFORM_HPUX
+#elif defined(sun) || defined(__sun__)
+# if defined(__SVR4) || defined(__svr4__)
+#  define TRIO_PLATFORM_SOLARIS
+# else
+#  define TRIO_PLATFORM_SUNOS
+# endif
+#endif
+
+#if defined(__STDC__) || defined(TRIO_COMPILER_MSVC) || defined(TRIO_COMPILER_BCB)
+# define TRIO_COMPILER_SUPPORTS_C89
+# if defined(__STDC_VERSION__)
+#  define TRIO_COMPILER_SUPPORTS_C90
+#  if (__STDC_VERSION__ >= 199409L)
+#   define TRIO_COMPILER_SUPPORTS_C94
+#  endif
+#  if (__STDC_VERSION__ >= 199901L)
+#   define TRIO_COMPILER_SUPPORTS_C99
+#  endif
+# elif defined(TRIO_COMPILER_SUNPRO)
+#  if (__SUNPRO_C >= 0x420)
+#   define TRIO_COMPILER_SUPPORTS_C94
+#  endif
+# endif
+#endif
+
+#if defined(_XOPEN_SOURCE)
+# if defined(_XOPEN_SOURCE_EXTENDED)
+#  define TRIO_COMPILER_SUPPORTS_UNIX95
+# endif
+# if (_XOPEN_VERSION >= 500)
+#  define TRIO_COMPILER_SUPPORTS_UNIX98
+# endif
+# if (_XOPEN_VERSION >= 600)
+#  define TRIO_COMPILER_SUPPORTS_UNIX01
+# endif
+#endif
+
+/*************************************************************************
+ * Generic defines
+ */
+
+#if !defined(TRIO_PUBLIC)
+# define TRIO_PUBLIC
+#endif
+#if !defined(TRIO_PRIVATE)
+# define TRIO_PRIVATE static
+#endif
+
+#if !(defined(TRIO_COMPILER_SUPPORTS_C89) || defined(__cplusplus))
+# define TRIO_COMPILER_ANCIENT
+#endif
+
+#if defined(TRIO_COMPILER_ANCIENT)
+# define TRIO_CONST
+# define TRIO_VOLATILE
+# define TRIO_SIGNED
+typedef double trio_long_double_t;
+typedef char * trio_pointer_t;
+# define TRIO_SUFFIX_LONG(x) x
+# define TRIO_PROTO(x) ()
+# define TRIO_NOARGS
+# define TRIO_ARGS1(list,a1) list a1;
+# define TRIO_ARGS2(list,a1,a2) list a1; a2;
+# define TRIO_ARGS3(list,a1,a2,a3) list a1; a2; a3;
+# define TRIO_ARGS4(list,a1,a2,a3,a4) list a1; a2; a3; a4;
+# define TRIO_ARGS5(list,a1,a2,a3,a4,a5) list a1; a2; a3; a4; a5;
+# define TRIO_ARGS6(list,a1,a2,a3,a4,a5,a6) list a1; a2; a3; a4; a5; a6;
+# define TRIO_VARGS2(list,a1,a2) list a1; a2
+# define TRIO_VARGS3(list,a1,a2,a3) list a1; a2; a3
+# define TRIO_VARGS4(list,a1,a2,a3,a4) list a1; a2; a3; a4
+# define TRIO_VARGS5(list,a1,a2,a3,a4,a5) list a1; a2; a3; a4; a5
+# define TRIO_VA_DECL va_dcl
+# define TRIO_VA_START(x,y) va_start(x)
+# define TRIO_VA_END(x) va_end(x)
+#else /* ANSI C */
+# define TRIO_CONST const
+# define TRIO_VOLATILE volatile
+# define TRIO_SIGNED signed
+typedef long double trio_long_double_t;
+typedef void * trio_pointer_t;
+# define TRIO_SUFFIX_LONG(x) x ## L
+# define TRIO_PROTO(x) x
+# define TRIO_NOARGS void
+# define TRIO_ARGS1(list,a1) (a1)
+# define TRIO_ARGS2(list,a1,a2) (a1,a2)
+# define TRIO_ARGS3(list,a1,a2,a3) (a1,a2,a3)
+# define TRIO_ARGS4(list,a1,a2,a3,a4) (a1,a2,a3,a4)
+# define TRIO_ARGS5(list,a1,a2,a3,a4,a5) (a1,a2,a3,a4,a5)
+# define TRIO_ARGS6(list,a1,a2,a3,a4,a5,a6) (a1,a2,a3,a4,a5,a6)
+# define TRIO_VARGS2 TRIO_ARGS2
+# define TRIO_VARGS3 TRIO_ARGS3
+# define TRIO_VARGS4 TRIO_ARGS4
+# define TRIO_VARGS5 TRIO_ARGS5
+# define TRIO_VA_DECL ...
+# define TRIO_VA_START(x,y) va_start(x,y)
+# define TRIO_VA_END(x) va_end(x)
+#endif
+
+#if defined(TRIO_COMPILER_SUPPORTS_C99) || defined(__cplusplus)
+# define TRIO_INLINE inline
+#elif defined(TRIO_COMPILER_GCC)
+# define TRIO_INLINE __inline__
+#elif defined(TRIO_COMPILER_MSVC)
+# define TRIO_INLINE _inline
+#elif defined(TRIO_COMPILER_BCB)
+# define TRIO_INLINE __inline
+#else
+# define TRIO_INLINE
+#endif
+
+/*************************************************************************
+ * Workarounds
+ */
+
+#if defined(TRIO_PLATFORM_VMS)
+/*
+ * Computations done with constants at compile time can trigger these
+ * even when compiling with IEEE enabled.
+ */
+# pragma message disable (UNDERFLOW, FLOATOVERFL)
+
+# if (__CRTL_VER < 80000000)
+/*
+ * Although the compiler supports C99 language constructs, the C
+ * run-time library does not contain all C99 functions.
+ *
+ * This was the case for 70300022. Update the 80000000 value when
+ * it has been accurately determined what version of the library
+ * supports C99.
+ */
+#  if defined(TRIO_COMPILER_SUPPORTS_C99)
+#   undef TRIO_COMPILER_SUPPORTS_C99
+#  endif
+# endif
+#endif
+
+/*
+ * Not all preprocessors supports the LL token.
+ */
+#if defined(TRIO_COMPILER_BCB)
+#else
+# define TRIO_COMPILER_SUPPORTS_LL
+#endif
+
+#endif /* TRIO_TRIODEF_H */