ip2unix: 2.1.1 -> 2.1.2

This fixes the issues with glibc 2.30, which were caused because glibc
no longer allows to dlopen/LD_PRELOAD a PIE executable.

So this release is essentially just a hotfix release which addresses
this issue by splitting the executable and library.

Signed-off-by: aszlig <aszlig@nix.build>
Reported-by: @zimbatm