Define _WCHAR_T in solaris/wchar.h.  This fixes a bug where Solaris 10 headers
try to define C++ keywords as typedefs (fixed in Solaris 11).

llvm-svn: 151890
diff --git a/libcxx/include/support/solaris/wchar.h b/libcxx/include/support/solaris/wchar.h
index 0af4ea8..05a7241 100644
--- a/libcxx/include/support/solaris/wchar.h
+++ b/libcxx/include/support/solaris/wchar.h
@@ -16,6 +16,7 @@
 #define wcswidth sun_wcswidth
 #define wcwidth sun_wcwidth
 #define wctype sun_wctype
+#define _WCHAR_T 1
 #include_next "wchar.h"
 #undef iswalpha 
 #undef iswupper