GCC 4.9 support

The following adds bits needed for GCC pre-4.9.0 support, fixes some already broken URLs. Tested on `slc6_amd64_gcc481` with `CMSSW_7_1_X_2014-01-27-0200` and all RelVals passed. Once in IB, `IB/CMSSW_7_1_X/stable` will be branched to `IB/CMSSW_7_1_X/gcc490` with only `gcc.spec` being different.