Overallocation in function get_exts()
There seems to be an oversized allocation in ```get_exts()``` at glad/lang/c/loader/gl.py, see line 57:
```char *local_str = (char*)malloc((len+1) * sizeof(*exts_i));```
The variable ```exts_i``` is of type ```const char **```, so ```sizeof (*exts_i)``` is equivalent to ```sizeof (const char *)```, but we just need ```sizeof (char)```. I would suggest to replace the line in question with:
```char *local_str = (char*)malloc((len+1) * sizeof(*local_str));```