make test shows test binary return codes
make test shows test binary return codes

Previously if your tests segfaulted, `make test` would return
successfully, and print a simple warning in white text mixed in with all
the other output.
This checks the return code from the test binary and prints a warning if
it's nonzero.

offa/cpputest,basvodde/cpputest,cpputest/cpputest,offa/cpputest,offa/cpputest,basvodde/cpputest,offa/cpputest,basvodde/cpputest,cpputest/cpputest,cpputest/cpputest,cpputest/cpputest,basvodde/cpputest