makechrootpkg: Inside chroot, make Git consider all repos safe

Git 2.45.1 expanded its security checks to deny cloning even local repos that are owned by another user. Previously, this just affected network filesystems.

On our buildserver, this prevents makepkg from cloning repos from our shared srcdest into the srcdir, if these repos were created by another packager.

To disable this check, set safe.directory to *. This looks like a glob, but is really just a special value. The only other option would be to add each Git repository in srcdest to the configuration.