Misc fixes to CXXFLAGS.

- Reduce line length.
- Add `-Werror=return-local-addr` since it seems correlated enough to
  actual issues.
Merge pull request #801 from ktf/add-return-local-addr-error

Misc fixes to CXXFLAGS.
Merge remote branch 'origin/IB/CMSSW_7_2_X/stable' into IB/CMSSW_7_0_X/stable