Prevent s390-specific stuff from being used on other architectures
Prevent s390-specific stuff from being used on other architectures

Otherwise things fail to build.

vpodzime/libblockdev,rhinstaller/libblockdev,atodorov/libblockdev,rhinstaller/libblockdev,rhinstaller/libblockdev,vpodzime/libblockdev,atodorov/libblockdev,vpodzime/libblockdev,atodorov/libblockdev