main/postmarketos-mkinitfs: add workaround for x86_64 qemu on aarch64

This adds a workaround for: qemu-project/qemu#2560

The tl;dr is that there's a qemu bug that prevents running mkinitfs (or any go apps) on a aarch64 host using qemu-x86_64. I've basically been unable to build x86_64 images on my aarch64 system for months now, which is less than ideal :(

Patch is in mkinitfs 2.6.1, but picked to the older version in master until !5636 (merged) is merged