There was no 3.1 for some reason. The old sed-based path patching was
broken and resulted in syntax errors since it was a bit over-eager.
Instead of fixing it, I decided to replace it with a patch file which is
easier to inspect and will fail in a more obvious way next time.
The patch is now applied unconditionally, since it actually applies to
all linux platforms. The changes are localized to linux-specific code,
so it does not hurt to apply it on non-linux platforms as well.
Hedgewars needs a small fix to work with the new version. Done in the
same commit to avoid a broken commit.
