devel/autoconf: Update to 2.73
cad/alliance, databases/proxysql, deskutils/growl-for-linux,
emulators/wine-proton, net/yate, sysutils/grub2-efi,
sysutils/grub2-pcbsd: Add USE_CSTD=gnu11 because autoconf 2.73 tries
to use C23 and these ports are broken with that.
PR: 293963
Exp-run by: antoine