Allow overriding of CMAKE_CREATE_CONSOLE_EXE and CMAKE_CREATE_WIN32_EXE
There is no way to actually correctly pass a subsystem version to lld-link using cmake. CMake defines CMAKE_CREATE_CONSOLE_EXE and CMAKE_CREATE_WIN32_EXE even if I am forcing the subsystem with -DCMAKE_EXE_LINKER_FLAGS for example, lld-link take the last occurence of /subsystem which is the one from CMAKE_CREATE_CONSOLE_EXE or CMAKE_CREATE_WIN32_EXE. Conditionnaly set CMAKE_CREATE_WIN32_EXE andCMAKE_CREATE_CONSOLE_EXE if they are not defined solves this issue.
Edited by Diorcet Yann