glcpp: Add new test showing bug where a trailing ':' prevents macro expansion

This demonstrates a bug that was recently triggered in piglit.

Here is the original bug report (containing a test case almost identical
to this one):

	https://bugs.freedesktop.org/show_bug.cgi?id=44764

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/glsl/glcpp/tests/100-macro-with-colon.c

@@ -0,0 +1,7 @@
+#define one 1
+#define two 2
+
+switch (1) {
+   case one + two:
+      break;
+}

src/glsl/glcpp/tests/100-macro-with-colon.c.expected

@@ -0,0 +1,8 @@
+
+
+
+switch (1) {
+ case 1 + 2:
+ break;
+}
+