Update GCC easyblock for gcc-4.9
GCC: update for 4.9.0 and ISL/CLooG
GCC: fix remarks
fix merge conflict
GCC: updated remarks
Merge branch 'gcc49' of https://github.com/boegel/easybuild-easyblocks into gcc49

* 'gcc49' of https://github.com/boegel/easybuild-easyblocks:
  fix remark
  fix GCC sanity check for versions prior to v4.2
  disable extra source dirs requirement for GCC versions older than 4.5
  improve debug message, also mention configure_cmd_prefix used
  add support for configure_cmd_prefix easyconfig parameter in ConfigureMake easyblock
GCC: drop tsan, lsan from sanity check
GCC: added exception for Debian too
GCC: don't check for lib64 dir in sanity check

We already check for files in that dir so it's redundant.
GCC: fix missing in
GCC: now really fix that line
Merge pull request #396 from wpoely86/gcc49

GCC 4.9.0