[Nmh-workers] bug in decode_rfc2047()

[David Levine]

I've been slow to adapt to the multibyte world, so I
tripped over a bug in decode_rfc2047():

  12  12/31 "Sears"            2013 New Year?s Deals! Start the yearr right

scan really did produce "yearr", wrongly.  valgrind noticed,
too.

The fix was to properly decrement a byte counter when
incrementing a corresponding buffer pointer.  If anyone
wants to review the fix:

http://git.savannah.gnu.org/cgit/nmh.git/commit/?id=3af3288f3acdfe29d3c17aefd9e0453ac3204541

David