nitg/ffi: intro of FFI with C++

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib: intro the cpp module to support C++ code

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
nitg/ffi: adds support for the cpp_compiler_options

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
tests: intro tests for FFI with C++

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
nitg: fix use only local files in generated Makefile (for C++)

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>