Mk/Scripts/qa.sh: Fix false positives in LIB_DEPENDS warnings

To warn when library dependencies may not be required, the proxydeps()
function compares the libraries listed in LIB_DEPENDS with those
reported by ldd. However, the list from ldd is sanitized to remove
version information from the library names, while the entries from
LIB_DEPENDS are not. This leads to comparisons such as libreadline.so.8
from LIB_DEPENDS versus libreadline.so from ldd, resulting in false
positives. Adjust the comparison to avoid such false-positive warnings.

Event: Kitchener-Waterloo Hackathon 202506
Reviewed by: emaste, rene
Approved by: portmgr (rene)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D50860