[lldb] Undef GetMessage when including Windows.h

GetMessage is a define that can expand to GetMessageA (ANSI) or
GetMessageW (wide). Avoid the issue when including this header by
undef'ing the macro.

Author: JDevlieghere

lldb/include/lldb/Host/windows/windows.h

@@ -17,9 +17,10 @@
 #undef NOMINMAX // undef a previous definition to avoid warning
 #define NOMINMAX
 #include <windows.h>
+#undef CreateProcess
+#undef GetMessage
 #undef GetUserName
 #undef LoadImage
-#undef CreateProcess
 #undef Yield
 #undef far
 #undef near