git-toolfile: pick different perl lib dir

On SLC6 distribution a different PERL5LIB path is picked.

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #119 from davidlt/IB/CMSSW_6_2_X/stable

[CMSSW_6_2_X] Fix GIT PERL5LIB path for SLC6.