OK, fixed test-mhfixmsg on Solaris 11, where BUFSIZ is 1024.

OK, fixed test-mhfixmsg on Solaris 11, where BUFSIZ is 1024.
The problem was in the content_encoding() function of mhfixmsg:
it would restart its counter of the characters on a line whenever
new characters were read in.  The fix was easy, just move the
initialization of that counter outside of the fread() loop.