Make srpmutil compile with newer rpm library.

Define _RPM_4_4_COMPAT in order to get some old types and declaration.
Change epoch from char* to uint32_t.
Remove some unused variables.

Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Merge pull request #3 from freddy77/rpm_compat

Make srpmutil compile with newer rpm library.