scripts/decodecode: make it take multiline Code line

In case of running scripts/decodecode without any parameters in order to
give a copy'n'pasted Code line from, for example, email it would parse
only first line of it, while in emails it's split to few.

ie, when you have a file out of oops the Code line looks like

  Code: hh hh ... <hh> ... hh\n

When copy'n'paste from, for example, email where sender or some middle
MTA split it, the line looks like:

  Code: hh hh ... hh\n
  hh ... <hh> ... hh\n
  hh hh ... hh\n

The Code line followed by another oops line usually contains characters
out of hex digit + space + < + > set.

So add logic to join this split back if and only if the following lines
have hex digits, or spaces, or '<', or '>' characters.  It will be quite
unlikely to have a broken input in well formed Oops or dmesg, thus a
simple regex is being used.

Link: http://lkml.kernel.org/r/20171212100323.33201-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>