New review comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/23485#discussion_r453219396

Comment:
Replace with
```
post_patch() {
	vsed -e 's|/usr/local|/usr|g' -i Makefile
	vsed -e 's|/usr/local/sbin|/usr/bin|' -i src/Makefile
}
```
Doing this in `post_patch` is logically consistent since it's a patch and will automatically place you in `$wrksrc` so the paths are simpler. Using `vsed` will verify that changes were actually made rather than silently proceeding if no matches are replaced.