gdb: update version to 7.6

Updates GDB version to 7.6.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
icc: added dummy icc tool and update icc-gcc-toolfile to use new tool
run glimse before relocation the src symlinks
Merge pull request #22 from davidlt/IB/CMSSW_6_2_X/slc6_amd64_gcc480

IB/CMSSW_6_2_X/slc6_amd64_gcc480: GDB 7.6 and ICC