Remove tab character.

asio/include/asio/detail/select_reactor.hpp

diff --git a/asio/include/asio/detail/select_reactor.hpp b/asio/include/asio/detail/select_reactor.hpp
index 389d079..9f0e4a4 100644
--- a/asio/include/asio/detail/select_reactor.hpp
+++ b/asio/include/asio/detail/select_reactor.hpp
@@ -21,7 +21,7 @@
   || (!defined(ASIO_HAS_DEV_POLL) \
       && !defined(ASIO_HAS_EPOLL) \
       && !defined(ASIO_HAS_KQUEUE) \
-	  && !defined(ASIO_WINDOWS_RUNTIME))
+      && !defined(ASIO_WINDOWS_RUNTIME))
 
 #include <cstddef>
 #include "asio/detail/fd_set_adapter.hpp"