Clang: Support old-style SIGNAL/SLOT macro

Color types and enable Ctrl+click for the functions
and types inside SIGNAL/SLOT macros.

Change-Id: Ic1c0b7372fe9a73c5607b1973d75a6656c75ef0e
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

share/qtcreator/cplusplus/wrappedQtHeaders/QtCore/qobjectdefs.h

@@ -61,6 +61,9 @@
 // static_assert can be found as a class child but does not add extra AST nodes for completion
 #define Q_PROPERTY(arg) static_assert("Q_PROPERTY", #arg);
 
+#define SIGNAL(arg) #arg
+#define SLOT(arg) #arg
+
 #pragma clang diagnostic pop
 
 #endif // WRAPPED_QOBJECT_DEFS_H