man: Remove old date from man page header

Closes #1483
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
tools: Define gitcommit for our work in progress srpms spec file

This way builders like Coverity and such can take the resulting
srpm and build it without special extra defines or flags.

Closes #1484
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>