Fix mess with ssl_version_short_names[] being defined multiple places

Fix mess with ssl_version_short_names[] being defined multiple places
now that it is no longer a static variable in packet-ssl-utils.h.
Leaving it as static caused a warning turned error that it was unused
in the current file (packet-ssl-utils.h).  Resolution: Move the variable
to packet-ssl.c and declare as extern in packet-dtls.c - the only other
place that needs it.

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@21161 f5534014-38df-0310-8fa8-9805f1628bb7