unused function 'has_ext' 
I'm getting a compiler warning of an unused function `has_ext`. I know I can just ignore the warning or turn it off, but do you think one could somehow avoid including a static function if it is actually not used anywhere in the file?

With these settings:

    http://glad.dav1d.de/#profile=compatibility&language=c&specification=gl&api=gl%3D3.3

I'm getting this warning:

```
glad.c:75:12: warning: unused function 'has_ext' [-Wunused-function]
static int has_ext(const char *ext) {
```