[cmake-developers] CheckTypeSize: Add support for C++

[Daniele E. Domenichelli]

Hello,

I'm trying to fix CheckTypeSize to support C++ in the same way I fixed
CheckStructHasMember.

I pushed the topic CheckTypeSize_CXX (including unit tests), can you
review it? The only thing I'm not convinced about is that I used
CMakeParseArguments, since CheckTypeSize already supports an extra
argument (BUILTIN_TYPES_ONLY) and manually parsing the arguments will be
a bit more complicated than for CheckStructHasMember. Do you think I
should parse it instead?

Thanks.

Regards,
 Daniele