compiler-flags.cmake: check for C++11 first
compiler-flags.cmake: check for C++11 first

darktable-org/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed,anarsoul/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,anarsoul/rawspeed,anarsoul/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed