cmake: add -fno-omit-frame-pointer to CXX Debug flags

Signed-off-by: Thomas Ingleby <thomas.c.ingleby@intel.com>
mraa_internal: add extern "C" to internal headers

Signed-off-by: Thomas Ingleby <thomas.c.ingleby@intel.com>
mraa: add mraa_init to the module initialisation.

Signed-off-by: Thomas Ingleby <thomas.c.ingleby@intel.com>
hook: rename from declared struct to adance_func

* Removed bitfield, now checks if pointer NULL.

Signed-off-by: Thomas Ingleby <thomas.c.ingleby@intel.com>