Log Message:
Update shells/scsh to 0.6.7.

New in this release
=====================
** Support for interix
** Ignoring of synchronous signals
   The procedures IGNORE-SIGNAL and HANDLE-SIGNAL-DEFAULT have been
   added.
** Support for gcc 4.0
** 0.6 for module path
   The standard module path now contains
   ${prefix}/lib/scsh/modules/0.6 in addition to
   $prefix/lib/scsh/modules for compatibility with install-lib
** New implementation of open-pty
   Instead of search for /dev/pty??, scsh now tries a wide variety of
   ways to aquire a new pty and the corresponding tty.
** Bug fixes
   argv[0] is now the first element of command-line
   Fixes found by new test suite
   Regexp for empty string
   Argument checking for COPY-BYTES!
   GC_PROTECTs for send_substring
   format_date support for #f timezone
   Added predicates for user-info and group-info
   Reaping of stopped processes: Do not mark stopped processes as dead
   md5-digest-for-port
   | regexps return char-sets
   standard-let in srfi-5
   (%)read-delimited! checks for mutable buffer
   leap second for srfi-19
   The default image for the scshvm is now the installed scsh.image.