Function call missing argument list warning
Tried to generate GL loader using Glad2, header only, core profile, and it gives the following warning [C4551 function call missing argument list](https://docs.microsoft.com/lv-lv/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4551?view=msvc-160) using MSVC 2019.

```diff
static int glad_gl_find_extensions_gl( int version) {
    const char *exts = NULL;
    unsigned int num_exts_i = 0;
    char **exts_i = NULL;
    if (!glad_gl_get_extensions(version, &exts, &num_exts_i, &exts_i)) return 0;

!    (void) glad_gl_has_extension;

    glad_gl_free_extensions(exts_i, num_exts_i);

    return 1;
}
```