Make glGet state queries buffer-safe

[SixSleepyAsh]

Summary

• Replaces raw glGet* calls with buffer-safe variants that avoid undefined behavior on mismatched return types
• Ensures all state queries write into correctly-sized buffers

Fixes #644

[adriengivry]

This will already be fixed by #824

Overload isn't accepting any changes to its HAL at the moment.

Thanks for your contribution!