src: Improve error reporting with cmocka default output
src: Improve error reporting with cmocka default output

Reviewed-by: Jakub Hrozek <17cd138b925932d6ed84ede56550124a0b538ee0@posteo.se>

jamesmunns/CMocka,dsch/cmocka,jamesmunns/CMocka,clibs/cmocka,wingyplus/cmocka,dsch/cmocka,wingyplus/cmocka,clibs/cmocka