Fix token-pasting macros not working in preprocessor directives. (#2453)

Fixes #2443

glslang/MachineIndependent/preprocessor/Pp.cpp

@@ -455,6 +455,7 @@ int TPpContext::eval(int token, int precedence, bool shortCircuit, int& res, boo
                 token = scanToken(ppToken);
             }
         } else {
+            token = tokenPaste(token, *ppToken);
             token = evalToToken(token, shortCircuit, res, err, ppToken);
             return eval(token, precedence, shortCircuit, res, err, ppToken);
         }