pseudo: Fix to work with glibc 2.38

pseudo: Fix to work with glibc 2.38

This adds a horrible hack to get pseudo working with glibc 2.38. We can't
drop _GNU_SOURCE to something like _DEFAULT_SOURCE since we need the defines
the gnu options bring in. That leaves using internal glibc defines to disable
the c23 versions of strtol/fscanf and friends. Which would break pseudo
build with 2.38 from running on hosts with older glibc.

We'll probably need to come up with something better but this gets glibc 2.38
and working and avoids autobuilder failures.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>