Tests: Fix RunCMake.CompileFeatures test NonValidTarget2 case

Mark the generated source file with the GENERATED property explicitly
since it is not marked automatically as the output of any custom
command.  Mark both the 0 and 1 variants so it works no matter the
outcome of the generator expression.
Features: Record for AppleClang 5.1

Apple's Clang 5.1 already supports most of the C and C++ features CMake
enumerates.
Merge topic 'AppleClang-5.1-features' into next

bd6b42c1 Features: Record for AppleClang 5.1
b341799e Tests: Fix RunCMake.CompileFeatures test NonValidTarget2 case