glsl: Add glcpp tests for a macro used twice

This test cases exposes a bug as described in this bug report:

	"ralloc.c:78: get_header: Assertion `info->canary == 0x5A1106'
	failed." when using a macro in GLSL
	https://bugs.freedesktop.org/show_bug.cgi?id=45082

Clearly, some memory is getting (incorrectly) freed on the first macro
invocation, leading to problems with the second macro invocation.

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

src/glsl/glcpp/tests/101-macros-used-twice.c

@@ -0,0 +1,16 @@
+#define object 1
+#define function(x) 1
+
+#if object
+once
+#endif
+#if object
+twice
+#endif
+
+#if function(0)
+once
+#endif
+#if function(0)
+once again
+#endif

src/glsl/glcpp/tests/101-macros-used-twice.c.expected

@@ -0,0 +1,17 @@
+
+
+
+
+once
+
+
+twice
+
+
+
+once
+
+
+once again
+
+