In new_format_oid(), handle a zero-length OID.

In new_format_oid(), handle a zero-length OID.

Fix a bug introduced recently in packet-rpc.c.

Replace DISSECTOR_ASSERT() with THROW(ReportedBoundsError) in my recent
checkins, since fuzz-test.sh sets WIRESHARK_ABORT_ON_DISSECTOR_BUG.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@18693 f5534014-38df-0310-8fa8-9805f1628bb7