.cpp files have spurious #ifdef __cplusplus

[terrillmoore]

The following files use #ifdef __cplusplus. This should be corrected, because .cpp files (unlike .h files) can not be anything else.

The C-isms should also be corrected.

• Don't use #define in C++ files unless there's no alternative. #define can almost always be replaced by constexpr
• Don't declare local functions extern "C" -- they can (and should) be C++, or even converted to private method functions.

My guess is that these are cut/paste errors after refactorings.

[terrillmoore]

I've corrected this. Will push a patches later today.