IAR: Fix building with IAR ARM 6.X

Use the correct version macros and version numbers.

Modules/Compiler/IAR-C.cmake

@@ -10,7 +10,7 @@ endif()
 
 set(CMAKE_C_EXTENSION_COMPILE_OPTION -e)
 
-if(CMAKE_CXX_COMPILER_VERSION_INTERNAL VERSION_GREATER 7)
+if(CMAKE_C_COMPILER_VERSION_INTERNAL VERSION_GREATER 7)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION --c89)
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION --c89 -e)
   set(CMAKE_C99_STANDARD_COMPILE_OPTION "")
@@ -20,7 +20,7 @@ elseif()
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION -e)
 endif()
 
-if(CMAKE_CXX_COMPILER_VERSION_INTERNAL VERSION_GREATER 8)
+if(CMAKE_C_COMPILER_VERSION_INTERNAL VERSION_GREATER 8)
   set(CMAKE_C11_STANDARD_COMPILE_OPTION "")
   set(CMAKE_C11_EXTENSION_COMPILE_OPTION -e)
 endif()

Modules/Compiler/IAR-CXX.cmake

@@ -8,7 +8,8 @@ if(NOT CMAKE_IAR_CXX_FLAG)
   if(NOT CMAKE_CXX_COMPILER_VERSION)
     message(FATAL_ERROR "CMAKE_CXX_COMPILER_VERSION not detected. This should be automatic.")
   endif()
-  if(CMAKE_CXX_COMPILER_VERSION_INTERNAL VERSION_GREATER 8)
+
+  if(CMAKE_CXX_COMPILER_VERSION_INTERNAL VERSION_GREATER 7)
     set(CMAKE_IAR_CXX_FLAG --c++)
   else()
     set(CMAKE_IAR_CXX_FLAG --eec++)