libclang parses like a C compiler

[theHolgi]

I looks like libclang incorporates a "C" compiler when parsing the sources.
This is a problem since the generated mockup.cc file will be compiled as C++; headers may parse differently dependent on the mode.

For example, the bool type from <stdbool.h> is #defined to int when parsed by libclang, but is a native type _Bool in C99 and C++ mode.

[build] /build/some_test/mockup.cc:21:5: error: functions that differ only in their return type cannot be overloaded
[build] int func_x(uint8_t arg){
[build] ~~~ ^
[build] /project/include/some_include.h:65:6: note: previous declaration is here
[build] bool func_x(uint8_t arg);
[build] ~~~~ ^

We need to control the compiler that libclang incorporates to be the same C++ compiler that will compile the code.