main/pixman: Add aarch64 NEON patch

Import the arm neon asm port for aarch64.

$simd feels hacky, not sure how to do it properly.

See also:

• https://gitlab.freedesktop.org/pixman/pixman/-/merge_requests/20
• https://salsa.debian.org/xorg-team/lib/pixman/-/merge_requests/1#note_215036