mesa-25.3.5 does not configure with gcc-15. It assumes clang

>>> Unpacking source... >>> Unpacking 'mesa-25.3.5.tar.xz' to /var/tmp/portage/media-libs/mesa-25.3.5/work >>> Source unpacked in /var/tmp/portage/media-libs/mesa-25.3.5/work >>> Preparing source in /var/tmp/portage/media-libs/mesa-25.3.5/work/mesa-25.3.5 ... >>> Source prepared. >>> Configuring source in /var/tmp/portage/media-libs/mesa-25.3.5/work/mesa-25.3.5 ... * abi_x86_64.amd64: running multilib-minimal_abi_src_configure cc1: error: ‘-Wno-error=incompatible-pointer-types-discards-qualifiers’: no option ‘-Wincompatible-pointer-types-discards-qualifiers’ * ERROR: media-libs/mesa-25.3.5::Miezhiko failed (configure phase): * (no error message)