* include/libvirt/virterror.h src/util/virterror.c: add a new error
VIR_ERR_CONFIG_UNSUPPORTED for valid but unsupported configuration options
* src/conf/domain_conf.c: Throw an error if guestfwd address isn't IPv4
and cleanup a number of parsing return error values.
We can slightly tighten up the regex's used to detect the use of
nonreentrant functions. We can also check src/util/virterror.c
by modifying a comment; I think it's worth it to get the additional
coverage.
Signed-off-by: Chris Lalancette <clalance@redhat.com>