merge bootp.h into print-bootp.c
Print checksum in hex, and print the actual checksum, plus cleanup
Check for TLV length too small.

The TLV length includes the T and the L, so it must be at least 4.

This means we don't need the "avoid infinite loop" check later; that
check was wrong, as per GitHub issue #401 and #402; this fixes #402,
which has a different patch for that bug.
Merge pull request #403 from superjamie/cdp-checksum-and-cleanup

Print CDP checksum in hex, print the actual checksum, cleanup
Merge git://github.com/the-tcpdump-group/tcpdump
Qualify "length" when printing it.

In the "the TLV length is too short" message, we're printing the length
of the entire TLV; report it as "TLV length".  If we pass that test,
we've subtracted out the lengths of the T and the L, leaving only the
length of the V, so report it as "value length".
Update to reflect the output format changes and bug fixes for CDP.
Use tabs consistently.
Add TLV length checks, fix another length check.
More #defines for CDP lengths and offsets.