build: rearrange spec file elements

This is majorly cleanup wrt spec file elements/definitions.  This
patch fixes to ease adding downstream specific conditions.

BUG: 1074939
Change-Id: I311abf8457417591a0d08569d3f83d73fa63cdc0
Signed-off-by: Bala.FA <barumuga@redhat.com>
Reviewed-on: http://review.gluster.org/7165
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>