[libc] Fix find_libc_version for checking each readable maps

[ValekoZ]

On a 2.30 libc, the string glibc 2.30 was on a r-x page instead of a r-- page.
Checking all readable pages would not affect performances too much since it is unlikely to have lots of libc maps, and this function is not called often.

[github-actions]

🤖 Coverage update for 786fc36 🔴

	Old	New
Commit	757f5bb	786fc36
Score	71.5302%	71.4923% (-0.0379)