BUILD: sym: Fix build on recent glibc

BUILD: sym: Fix build on recent glibc

With a recent glibc, as found on Ubuntu 26.04, with the default locale,
sort and comm do not always agree on the ordering of all characters,
notably punctuation characters, and comm will thus fail when reading the
output of sort, producing a warning, and prevent the minidebug section
from being created.
Just force them to use the C locale, where this is not a problem.