Add test for an object-like macro with a definition beginning with '('

Our current parser sees "#define foo (" as an identifier token
followed by a '(' token and parses this as a function-like macro.

That would be correct for "#define foo(" but the preprocessor
specification treats this whitespace as significant here so this test
currently fails.

tests/015-define-object-with-parens.c

@@ -0,0 +1,2 @@
+#define foo ( ) 1
+foo()