Use of 'extern "C"' and MATIO_NORETURN in C++ build about matio

[tbeu]

@sjoelund The [[noreturn]] case was copied from ModelicaUtilities.h. Can you please inspect and comment on it. Thanks.

[sjoelund]

Yes, I think for C++, extern "C" needs to be the first part of the declaration. It's more conceptual to extern "C" { declaration }, whereas in C, extern is just a part of the declaration. It did work with clang++ -std=c++11 and g++ with default std; only breaks with g++ -std=c++11.

[tbeu]

I hopefully fixed the C++ compilation in branch fix-c++. Please test and confirm if it works for you.

[gsjaardema]

Yes, works for me. Thanks.

Note that I'm not compiling matio with a C++ compiler; I'm using matio in a C++ application, so only the changes related to matio.h and matio_pubconf.h affect my use.

The additional changes related to being able to compile matio with a C++ compiler are nice, but I don't use those and I didn't test that -- all I tested was including matio.h in a C++ application which is what was failing for me previously.

[tbeu]

Fixed by 07728a3.