x11/gmrun: Fix position on multihead

Add a patch to make gmrun to show on current desktop instead of a static
place to help people using it on multihead environment.

PR: 259115
Obtained from: https://aur.archlinux.org/cgit/aur.git/tree/center-and-multihead.patch?h=gmrun-multihead
Sponsored by: Rubicon Communications, LLC ("Netgate")