VS10: Use expected values for UseOfMfc (#11213)

Use expected values for the UseOfMfc xml element in
VS 10 .vcxproj files.

  CMAKE_MFC_FLAG=1 maps to "Static"
  CMAKE_MFC_FLAG=2 maps to "Dynamic"
  all other values map to "false"

Thanks to Randy Schott and McBen for their patches which
served as inspiration and motivation for getting this done.

See also http://public.kitware.com/Bug/view.php?id=11224

Source/cmVisualStudio10TargetGenerator.cxx

@@ -290,16 +290,24 @@ void cmVisualStudio10TargetGenerator::WriteProjectConfigurationValues()
       }
     configType += "</ConfigurationType>\n";
     this->WriteString(configType.c_str(), 2); 
+
     const char* mfcFlag = 
       this->Target->GetMakefile()->GetDefinition("CMAKE_MFC_FLAG");
-    if(mfcFlag)
+    std::string mfcFlagValue = mfcFlag ? mfcFlag : "0";
+
+    std::string useOfMfcValue = "false";
+    if(mfcFlagValue == "1")
       {
-      this->WriteString("<UseOfMfc>true</UseOfMfc>\n", 2);
+      useOfMfcValue = "Static";
       }
-    else
+    else if(mfcFlagValue == "2")
       {
-      this->WriteString("<UseOfMfc>false</UseOfMfc>\n", 2);
+      useOfMfcValue = "Dynamic";
       }
+    std::string mfcLine = "<UseOfMfc>";
+    mfcLine += useOfMfcValue + "</UseOfMfc>\n";
+    this->WriteString(mfcLine.c_str(), 2);
+
     if(this->Target->GetType() <= cmTarget::MODULE_LIBRARY &&
        this->ClOptions[*i]->UsingUnicode())
       {