Reset platform/compiler info status for each language

In each CMake<lang>Information.cmake file we use an _INCLUDED_FILE
variable to track whether a compiler information file has been loaded.
Reset this variable for each language.

This fixes Fortran under VS generators with the Intel plugin.
Previously the variable would be left set true from C and C++ and then
Fortran would not load old-style files like Platform/Windows-ifort.

Modules/CMakeCInformation.cmake

@@ -26,6 +26,8 @@ ELSE(UNIX)
   SET(CMAKE_C_OUTPUT_EXTENSION .obj)
 ENDIF(UNIX)
 
+SET(_INCLUDED_FILE 0)
+
 # Load compiler-specific information.
 IF(CMAKE_C_COMPILER_ID)
   INCLUDE(Compiler/${CMAKE_C_COMPILER_ID}-C OPTIONAL)

Modules/CMakeCXXInformation.cmake

@@ -26,6 +26,8 @@ ELSE(UNIX)
   SET(CMAKE_CXX_OUTPUT_EXTENSION .obj)
 ENDIF(UNIX)
 
+SET(_INCLUDED_FILE 0)
+
 # Load compiler-specific information.
 IF(CMAKE_CXX_COMPILER_ID)
   INCLUDE(Compiler/${CMAKE_CXX_COMPILER_ID}-CXX OPTIONAL)

Modules/CMakeFortranInformation.cmake

@@ -16,6 +16,8 @@
 # It also loads the available platform file for the system-compiler
 # if it exists.
 
+SET(_INCLUDED_FILE 0)
+
 # Load compiler-specific information.
 IF(CMAKE_Fortran_COMPILER_ID)
   INCLUDE(Compiler/${CMAKE_Fortran_COMPILER_ID}-Fortran OPTIONAL)