when checking if -std=c++11 compiler option exist use the compiler that is selected via --with-cxx if set.
when checking if -std=c++11 compiler option exist use the compiler that is
selected via --with-cxx if set.


git-svn-id: ecbadac9c76e8cf640a0bca86f6bd796c98521e3@45166 27541ba8-7e3a-0410-8455-c3a389f83636

bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT,bbannier/ROOT