Michael van der Westhuizen:  Patches for Linux.  Fixes http://llvm.org/bugs/show_bug.cgi?id=14648.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@172435 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__config b/include/__config
index 203be76..8617b86 100644
--- a/include/__config
+++ b/include/__config
@@ -66,6 +66,12 @@
 #  endif
 #endif  // _WIN32
 
+#ifdef __linux__
+#  if defined(__GNUC__) && _GNUC_VER >= 403
+#    define _LIBCP_HAS_IS_BASE_OF
+#  endif
+#endif
+
 #ifdef __sun__
 # include <sys/isa_defs.h>
 # ifdef _LITTLE_ENDIAN