glcpp: Make standalone binary use preprocess().
This prevents the two code paths from getting out of sync. Also, future
work will need the shader source as a string anyway.
Unfortunately, this copies and pastes load_text_file from main.cpp, with
small changes (support for reading from stdin, talloc).
diff --git a/glcpp/glcpp.h b/glcpp/glcpp.h
index bb0ac95..2cfa98d 100644
--- a/glcpp/glcpp.h
+++ b/glcpp/glcpp.h
@@ -167,6 +167,9 @@
void
glcpp_parser_destroy (glcpp_parser_t *parser);
+int
+preprocess(void *talloc_ctx, const char **shader, char **info_log);
+
/* Functions for writing to the info log */
void