install_pmbootstrap: mark pmaports as safe dir

In latest git version a safety check was added that makes sure a git
directory is owned by the same user that tries to modify it. Since this
script runs only in CI, we can just mark it as safe directory and it
should work the same as before.

Fix for:
  Creating pmos user
  Found pmaports.cfg in current dir
  ERROR: failed to add original remote with git!
  fatal: unsafe repository ('/builds/anjandev/pmaports' is owned by someone else)
  To add an exception for this directory, call:
    git config --global --add safe.directory /builds/anjandev/pmaports

Related: https://gitlab.com/anjandev/pmaports/-/jobs/2328801751

install_pmbootstrap.sh

@@ -20,6 +20,11 @@ add_remote_origin_original() {
 		return
 	fi
 
+	# Mark pmaports dir as 'safe directory', so git doesn't complain about
+	# it being owned by another user.
+	git config --global --add safe.directory "$pmaports"
+	su pmos -c "git config --global --add safe.directory '$pmaports'"
+
 	# Add the remote, display the output only on error
 	if ! git -C "$pmaports" \
 		remote add -f origin-original \