FindMFC: Check for static MFC variant

Some CMake applications can set /MT without setting CMAKE_MFC_FLAG.
This change lets FindMFC work in those situations.

Modules/FindMFC.cmake

@@ -31,6 +31,7 @@ if(MFC_ATTEMPT_TRY_COMPILE)
     configure_file(${CMAKE_ROOT}/Modules/CheckIncludeFile.cxx.in
       ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckIncludeFile.cxx)
     message(STATUS "Looking for MFC")
+    # Try both shared and static as the root project may have set the /MT flag
     try_compile(MFC_HAVE_MFC
       ${CMAKE_BINARY_DIR}
       ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckIncludeFile.cxx
@@ -38,6 +39,16 @@ if(MFC_ATTEMPT_TRY_COMPILE)
       -DCMAKE_MFC_FLAG:STRING=2
       -DCOMPILE_DEFINITIONS:STRING=-D_AFXDLL
       OUTPUT_VARIABLE OUTPUT)
+    if(NOT MFC_HAVE_MFC)
+      configure_file(${CMAKE_ROOT}/Modules/CheckIncludeFile.cxx.in
+        ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckIncludeFile.cxx)
+      try_compile(MFC_HAVE_MFC
+        ${CMAKE_BINARY_DIR}
+        ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckIncludeFile.cxx
+        CMAKE_FLAGS
+        -DCMAKE_MFC_FLAG:STRING=1
+        OUTPUT_VARIABLE OUTPUT)
+    endif()
     if(MFC_HAVE_MFC)
       message(STATUS "Looking for MFC - found")
       set(MFC_HAVE_MFC 1 CACHE INTERNAL "Have MFC?")

Tests/MFC/CMakeLists.txt.in

@@ -45,6 +45,11 @@ set(files
 
 set(CMAKE_MFC_FLAG "@CMAKE_MFC_FLAG_VALUE@")
 
+FIND_PACKAGE(MFC)
+IF (NOT MFC_FOUND)
+  MESSAGE(FATAL_ERROR "MFC Could not be found during the MFC test")
+ENDIF()
+
 if("${CMAKE_MFC_FLAG}" STREQUAL "1")
   msvc_link_to_static_crt()
 else()