Print packets for unsupported link-layer protocols in hexadecimal/ASCII

Print packets for unsupported link-layer protocols in hexadecimal/ASCII

This avoids to get only:
tcpdump: packet printing is not supported for link type XYZ: use -w

The default printing is like:
18:45:52.723872 UNSUPPORTED
        0x0000:  001f 0000 0540 6078 725d 586d 4d66 4671  .....@`xr]XmMfFq
        0x0010:  6d58 4d5c 7159 5f71 565c 556c 4e71 7171  mXM\qY_qV\UlNqqq
        0x0020:  7171 7171 7171 7171 7171 7171 7171 5180  qqqqqqqqqqqqqqQ.
        0x0030:  7f7f                                     ..
18:45:52.755995 UNSUPPORTED
        0x0000:  001f 0000 0540 6043 7851 807f 7f         .....@`CxQ...
        [...]