loader: gc loader_get_extensions_name() and __DRI_DRIVER_{GET_,}EXTENSIONS defines
Leaving the defines in include/GL/internal/dri_interface.h because I'm not sure if something needs it.
Fixes: fa541a88 ("loader: delete loader_open_driver()")
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Leaving the defines in include/GL/internal/dri_interface.h because I'm not sure if something needs it.
Fixes: fa541a88 ("loader: delete loader_open_driver()")