Introduce `verify-ldso-abi.sh` script and architecture-specific baseline
files to the build.
This new verification step is integrated into the `%check` phase of the
glibc build process. It uses `gdb` to dump the internal ABI layout of
critical dynamic linker data structures (`_rtld_global_ro`,
`_rtld_global`, `struct link_map`, `struct pthread`) and compares them
against a predefined baseline.
This ensures that unintentional ABI breaks in `ld.so` are detected
early, maintaining stability for internal glibc components. The script
also supports generating new baselines when changes are intentional.
Resolves: RHEL-72564
