packaging: setup: raise shmmax to 40Mb

Raising shmmax requirements for supporting
RHEL-6.5 postgresql.

Change-Id: Ib7e033873bd393eba20b5704b57ee29968a59267
Bug-Url: https://bugzilla.redhat.com/1027605
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>