InstallRequiredSystemLibraries.cmake tries to install non-existent MFC DLL on Visual Studio 2017

Hi,

InstallRequiredSystemLibraries.cmake gives the following warning when CMAKE_INSTALL_MFC_LIBRARIES is set. I'm using Visual Studio 15.6.3.

1> CMake Warning at C:/Program Files (x86)/Microsoft Visual Studio/2017/Professional/Common7/IDE/CommonExtensions/Microsoft/CMake/CMake/share/cmake-3.10/Modules/InstallRequiredSystemLibraries.cmake:567 (message):
1>   system runtime library file does not exist: 'C:/Program Files
1>   (x86)/Microsoft Visual
1>   Studio/2017/Professional/VC/Redist/MSVC/14.13.26020/Debug_NonRedist/x86/Microsoft.VC141.DebugMFC/mfcm140d.dll'
1> Call Stack (most recent call first):
1>   _dep/bb/core/build/bb_install_runtime_dlls.cmake(8): (include)
1>   CMakeLists.txt(66): (bb_install_runtime_dlls)
1> 
1> 
1> MFC: C:/Program Files (x86)/Microsoft Visual Studio/2017/Professional/VC/Redist/MSVC/14.13.26020/x86/Microsoft.VC141.MFC

The directory C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\VC\Redist\MSVC\14.13.26020\debug_nonredist\x86\Microsoft.VC141.DebugMFC contains the following files only:

• mfc140d.dll
• mfc140ud.dll
• mfcm140ud.dll

Apparently, there is a check in the current implementation whether ${MSVC_MFC_DIR}/mfc${v}d.dll exists and it is assumed that ${MSVC_MFC_DIR}/mfcm${v}d.dll also exists (which is not the case).