mesa/glsl: rename preprocess to glcpp_preprocess

This symbol with dricore escapes into the namespace, its too generic,
we should prefix it with something just to be nice.

Should be applied to stable + 9.0

Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/glsl/glcpp/glcpp.c

@@ -111,7 +111,7 @@ main (int argc, char *argv[])
 	if (shader == NULL)
 	   return 1;
 
-	ret = preprocess(ctx, &shader, &info_log, NULL, API_OPENGL);
+	ret = glcpp_preprocess(ctx, &shader, &info_log, NULL, API_OPENGL);
 
 	printf("%s", shader);
 	fprintf(stderr, "%s", info_log);