common: create directory structure for rpmbuild

rpmbuild version 4.4.2.3 requires to create directory
structure before invoking when _topdir is defined.

Fixes: pmem/issues#3
Merge pull request #22 from plebioda/fix-make-rpm-on-sles11sp3

common: create directory structure for rpmbuild
blk: align ZERO and ERROR bit defs with spec

Thanks to alert reader @stellarhopper for this one!