graphics/gowall: fix build on armv7

Same issue as on i386, probably also applies to powerpc.
The patch could be applied unconditionally.
An upstream bug report was filed.

While we are at it, exclude option ONNX on i386 as the port
misc/onnx-runtime required for this option to work is currently
broken there.

Approved by: portmgr (build fix blanket)
MFH: 2026Q3
See also: https://github.com/gen2brain/go-fitz/issues/152

(cherry picked from commit 2bf74addd2ca6d695d4d34ac68455b7c3c2f524f)