New review comment by Chocimier on void-packages repository

https://github.com/void-linux/void-packages/pull/23983#discussion_r466616583

Comment:
```
post_patch() {
	vsed -i GNUmakefile -e "s|-I/usr/include|-I${XBPS_CROSS_BASE}/usr/include|g"
}
```

fixes cross build