The official gstreamer .pkg distribution should contain
'relocatable' dylibs, but as discovered in #29732,
some dylibs have absolute links to liblzma.5.dylibs

Since /opt/homebrew is the default install location
on Apple Silicion, this will cause the packaging &
build steps to fail, even if 'xz' package is installed
via homebrew.

This is a temporary fix until upstream fixes the bug
and makes the package truly 'relocatable'.

Signed-off-by: Mukilan Thiyagarajan <me@mukilan.in>