LOCAL: include <poll.h> rather than <sys/poll.h>

This make musl happy.
musl doesn't like including <sys/poll.h> directly:

  #warning redirecting incorrect #include <sys/poll.h> to <poll.h>

Change-Id: Ieef8163c0345085ed7c8f437cc2542f0346429ea

asio/include/asio/detail/socket_types.hpp

diff --git a/asio/include/asio/detail/socket_types.hpp b/asio/include/asio/detail/socket_types.hpp
index 57cf877..883277f 100644
--- a/asio/include/asio/detail/socket_types.hpp
+++ b/asio/include/asio/detail/socket_types.hpp
@@ -58,7 +58,7 @@
 #else
 # include <sys/ioctl.h>
 # if !defined(__SYMBIAN32__)
-#  include <sys/poll.h>
+#  include <poll.h>
 # endif
 # include <sys/types.h>
 # include <sys/stat.h>