Add tests for the structure of function-like macros.

These test only the most basic aspect of parsing of function-like
macros.  Specifically, none of the definitions of these function like
macros use the arguments of the function.

No function-like macros are implemented yet, so all of these fail for
now.

tests/011-define-func-empty.c

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

tests/012-define-func-no-args.c

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

tests/013-define-func-1-arg-unused.c

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

tests/014-define-func-2-arg-unused.c

@@ -0,0 +1,2 @@
+#define foo(x,y) 1
+foo(bar,baz)