SCRAMV1: add BuildRequires on gmake

gmake must be used from CMSDIST as it's not required or/and provided
on the target system.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
Merge pull request #1154 from davidlt/fix-scram

SCRAMV1: add BuildRequires on gmake
Merge remote branch 'origin/IB/CMSSW_7_3_X/stable' into IB/CMSSW_7_0_X/stable