InstallRequiredSystemLibraries: Split MFC redist dir variable

Modules/InstallRequiredSystemLibraries.cmake

@@ -383,13 +383,15 @@ if(MSVC)
       set(v "${_MFC_DLL_VERSION}")
       set(vs "${_MFC_IDE_VERSION}")
 
+      set(MSVC_REDIST_MFC_DIR "${MSVC_REDIST_DIR}")
+
       # Multi-Byte Character Set versions of MFC are available as optional
       # addon since Visual Studio 12.  So for version 12 or higher, check
       # whether they are available and exclude them if they are not.
 
       if(CMAKE_INSTALL_DEBUG_LIBRARIES)
         set(MSVC_MFC_DIR
-          "${MSVC_REDIST_DIR}/Debug_NonRedist/${CMAKE_MSVC_ARCH}/Microsoft.VC${vs}0.DebugMFC")
+          "${MSVC_REDIST_MFC_DIR}/Debug_NonRedist/${CMAKE_MSVC_ARCH}/Microsoft.VC${vs}0.DebugMFC")
         set(__install__libs ${__install__libs}
           "${MSVC_MFC_DIR}/mfc${v}ud.dll"
           "${MSVC_MFC_DIR}/mfcm${v}ud.dll"
@@ -402,7 +404,7 @@ if(MSVC)
         endif()
       endif()
 
-      set(MSVC_MFC_DIR "${MSVC_REDIST_DIR}/${CMAKE_MSVC_ARCH}/Microsoft.VC${vs}0.MFC")
+      set(MSVC_MFC_DIR "${MSVC_REDIST_MFC_DIR}/${CMAKE_MSVC_ARCH}/Microsoft.VC${vs}0.MFC")
       if(NOT CMAKE_INSTALL_DEBUG_LIBRARIES_ONLY)
         set(__install__libs ${__install__libs}
           "${MSVC_MFC_DIR}/mfc${v}u.dll"
@@ -417,7 +419,7 @@ if(MSVC)
       endif()
 
       # include the language dll's as well as the actuall dll's
-      set(MSVC_MFCLOC_DIR "${MSVC_REDIST_DIR}/${CMAKE_MSVC_ARCH}/Microsoft.VC${vs}0.MFCLOC")
+      set(MSVC_MFCLOC_DIR "${MSVC_REDIST_MFC_DIR}/${CMAKE_MSVC_ARCH}/Microsoft.VC${vs}0.MFCLOC")
       set(__install__libs ${__install__libs}
         "${MSVC_MFCLOC_DIR}/mfc${v}chs.dll"
         "${MSVC_MFCLOC_DIR}/mfc${v}cht.dll"