devel/glib20: Remove stale patch

This patch was added in 2002: https://github.com/freebsd/freebsd-ports/commit/e8da18edcdce6c3c96bc3629f0f5927901b2c60e#diff-a853c7b9fa72c4c63b38cd1188eaca75badf06e003cbdf880b9e0a6f44c1034b

The current unpatched code does the same thing as patched one plus some locking

Tested by: arrowd
Sponsored by: Serenity Cybersecurity, LLC