Makefile: Create SRPM repository metadata after all SRPMS are created
Makefile: Create SRPM repository metadata after all SRPMS are created

It is not necessary to rebuild the SRPM repository metadata
after each SRPM is built.   Build it once, at the end.

Signed-off-by: Euan Harris <c3b6e83069c8e9e3af49a38fec6026be89559638@citrix.com>

simonjbeaumont/planex,djs55/planex,djs55/planex,simonjbeaumont/planex,djs55/planex,simonjbeaumont/planex