VS: Fix MSVC_IDE definition recently broken by refactoring

In commit 485a940e (VS: Simplify MSVC version reporting, 2012-08-23) we
accidentally flipped the 0/1 values of MSVC_IDE.  Flip them back and
teach the CheckCompilerRelatedVariables test to check the variable.

Modules/Platform/Windows-MSVC.cmake

@@ -56,9 +56,9 @@ enable_language(RC)
 set(CMAKE_COMPILE_RESOURCE "rc <FLAGS> /fo<OBJECT> <SOURCE>")
 
 if("${CMAKE_GENERATOR}" MATCHES "Visual Studio")
-  set(MSVC_IDE 0)
-else()
   set(MSVC_IDE 1)
+else()
+  set(MSVC_IDE 0)
 endif()
 
 if(NOT MSVC_VERSION)

Tests/CheckCompilerRelatedVariables/CMakeLists.txt

@@ -46,6 +46,7 @@ echo_var(MSVC80)
 echo_var(MSVC90)
 echo_var(MSVC10)
 echo_var(MSVC11)
+echo_var(MSVC_IDE)
 
 if(MSVC)
   #
@@ -60,6 +61,13 @@ if(MSVC)
   else()
     message(FATAL_ERROR "error: ${msvc_total} MSVC** variables are defined -- exactly 1 expected")
   endif()
+  if(NOT DEFINED MSVC_IDE)
+    message(FATAL_ERROR "MSVC_IDE not defined but should be!")
+  elseif("${CMAKE_GENERATOR}" MATCHES "Visual Studio" AND NOT MSVC_IDE)
+    message(FATAL_ERROR "MSVC_IDE is not true but should be (${CMAKE_GENERATOR})!")
+  elseif(NOT "${CMAKE_GENERATOR}" MATCHES "Visual Studio" AND MSVC_IDE)
+    message(FATAL_ERROR "MSVC_IDE is true but should not be (${CMAKE_GENERATOR})!")
+  endif()
 else()
   #
   # The compiler is something other than cl... None of the MSVC** variables
@@ -70,6 +78,9 @@ else()
   else()
     message(FATAL_ERROR "error: ${msvc_total} MSVC** variables are defined -- exactly 0 expected")
   endif()
+  if(DEFINED MSVC_IDE)
+    message(FATAL_ERROR "MSVC_IDE is defined but should not be!")
+  endif()
 endif()