Backport CGAL from CMSSW_7_0_X

The following commit backports CGAL (incl. build time dependencies
gmp-static and mpfr-static) from CMSSW_7_0_X to CMSSW_5_3_X.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #172 from davidlt/backport-cgal-from-70x-to-53x

[CMSSW_5_3_X] Backport CGAL from CMSSW_7_0_X