temporary work around for clang 3.4 which is not parsing
[[cms::thread_guard(" var ")]] correctly and causing an error from clang
Merge pull request #3634 from gartung/MagneticField-clang-workaround

Static Analyser -- Temporary work around for clang 3.4 which is not parsing
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X