glcpp: Rename "errors" to "info_log."

Eventually, we'll want to be be able to print out warnings as well.
diff --git a/glcpp/glcpp.c b/glcpp/glcpp.c
index d204eee..8ba4661 100644
--- a/glcpp/glcpp.c
+++ b/glcpp/glcpp.c
@@ -36,7 +36,7 @@
 	ret = glcpp_parser_parse (parser);
 
 	printf("%s", parser->output);
-	fprintf(stderr, "%s", parser->errors);
+	fprintf(stderr, "%s", parser->info_log);
 
 	glcpp_parser_destroy (parser);