Fix detection of "std" flag in CMAKE_CXX_FLAGS
Fix detection of "std" flag in CMAKE_CXX_FLAGS

re-ordered the loop so that the "std" flag did not have to be the last
one to be detected.

kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix