Optionally, accept protocols that don't have a known name.
Avoid any allocations in the common case.
Return more granular error codes: -ERANGE for negative values,
-EOPNOTSUPP if the protocol is a valid number, but we don't know
the protocol, and -EINVAL only if it's not a numerical string.
This converts to TEST macro where it is trivial.
Some additional notable changes:
- simplify HAVE_LIBIDN #ifdef in test-dns-domain.c
- use saved_argc/saved_argv in test-copy.c, test-path-util.c,
test-tmpfiles.c and test-unit-file.c
Zbigniew Jędrzejewski-Szmek
Jan Janssen
Yu Watanabe