glibc check: alternatives to ldd needed

We use `ldd` to determine glibc's version. While this is commonly available, it may be missing on some minimal Linux distros. It would be good for us to provide fallbacks so we can still determine the glibc version.

This was reported via uv, where a user was using WolfiOS with no `ldd` by default: https://github.com/astral-sh/uv/issues/7903

No source file or test is named in the issue. Start by locating the ldd-based glibc version check, then review the WolfiOS report in uv issue 7903; done means the version can still be determined on minimal Linux systems without ldd, with coverage for the fallback behavior.

Written by the indexing model from the issue text.