glcpp: Print errors on stdout instead of stderr (non-standalone version).

Otherwise, piglit marks tests as "warn" when the shader was (correctly)
failing.
diff --git a/glcpp/pp.c b/glcpp/pp.c
index 7211bdb..04ea0a4 100644
--- a/glcpp/pp.c
+++ b/glcpp/pp.c
@@ -33,7 +33,7 @@
 	glcpp_parser_parse (parser);
 
 	errors = parser->errors[0] != '\0';
-	fprintf(stderr, "%s", parser->errors);
+	printf("%s", parser->errors);
 
 	talloc_steal(talloc_ctx, parser->output);
 	*shader = parser->output;