util: Allow port allocator to skip bind() check

util: Allow port allocator to skip bind() check

Test suites using the port allocator don't want to have different
behaviour depending on whether a port is in use on the host. Add
a VIR_PORT_ALLOCATOR_SKIP_BIND_CHECK which test suites can use
to skip the bind() test. The port allocator will thus only track
ports in use by the test suite process itself. This is fine when
using the port allocator to generate guest configs which won't
actually be launched

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Jim Fehlig <jfehlig@suse.com>