lib/transaction_package_replace.c: simplify.
Make sure that modified symlinks are preserved.

When removing a package, symlinks owned by this package that have been
modified should be preserved, unless the force flag is set via xbps-remove(8).
unpack: get rid of code that checks for modified symlinks.

Unpacking those symlinks is so cheap that there's no point in wasting
resources just to check if those have been modified, just unpack them
unconditionally.