CMake: fixing c++11 flag when compiling with ccache and g++
CMake: fixing c++11 flag when compiling with ccache and g++

Former-commit-id: aff57fb6a77e954ed94c8acc2ff66334f7e166f5
FabienPean/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,Anatoscope/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,hdeling/sofa,Anatoscope/sofa,FabienPean/sofa,Anatoscope/sofa,Anatoscope/sofa,hdeling/sofa,hdeling/sofa,hdeling/sofa,hdeling/sofa,Anatoscope/sofa,Anatoscope/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa,Anatoscope/sofa