config.map: add slc5_amd64_gcc481

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
Merge pull request #170 from davidlt/add-slc5_amd64_gcc481

[CMSSW_7_0_X] config.map: add slc5_amd64_gcc481
Merge remote-tracking branch 'origin/IB/CMSSW_7_0_X/stable' into IB/CMSSW_7_0_X/devel-gcc472