CompileFeatures: Record when Intel gained full CXX14 support

Use the infrastructure added by commit 646fb1a646 (CompileFeatures:
memoize C++ compilers with full language level support, 2019-03-27) to
avoid using a `try_compile` to check for C++14 feature support when the
running compiler is known to have all features.

Modules/Compiler/Intel-CXX.cmake

@@ -40,13 +40,7 @@ else()
     set(CMAKE_CXX17_EXTENSION_COMPILE_OPTION "-std=gnu++17")
   endif()
 
-  # While full C++14 support was first introduced in Intel 17,
-  # Intel 18.0.0-4 don't have full support as they broke
-  # support for cxx_relaxed_constexpr.
-  if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 18.0.4)
-    set(CMAKE_CXX14_STANDARD__HAS_FULL_SUPPORT ON)
-  elseif(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 17.0.0
-        AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 18.0.0)
+  if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 17.0)
     set(CMAKE_CXX14_STANDARD__HAS_FULL_SUPPORT ON)
   endif()