Update of port mail/mutt-devel. This update fixes:

- detection of libraries by configure.
- superflouous installation of some html files.
- additional doc files when NNTP support is wanted.
- fix the missing ca-locale file in pkg-plist.

These four were submitted by Vsevolod Volkov <vvv@mutt.org.ua>.

Also changed:
- WITH_MUTT_SLANG is now the default (which can be changed by
  defining WITHOUT_MUTT_SLANG)
- fixed the usage of WITH_MUTT_NCURSES (ncurses is part of the base
  system since 4.0)
- WITH_MUTT_SSL is included when PACKAGE_BUILDING is defined
- some hints which knobs are available at the beginning of the
  Makefile