Incorporate and use command-line-processor proposed for Guile core

Since the elimination of the C wrapping around mcron and all the
executable scripts, a weakness in Guile's (ice-9 getopt-long) module
means that the command 'mcron -s crontab.scm' does not currently
work.  A replacement for the getopt-long module, as well as a
higher-level 'command-line-processor' facility, have been pushed to
the Guile upstream developers and are awaiting approval and
incorporation.  In the meantime, those modules are temporarily
incorporated here into the mcron package, and the code is modified
to use those local versions.

 * Makefile.am: install two new Guile modules
 * src/{cron,crontab,mcron}.in: use local command-line-processor module
 * src/mcron/command-line-processor.scm: new module
 * src/mcron/getopt-long.scm: new module
 * tests/schedule{,-2}.sh: clarify tests of -s, --schedule options

tests/schedule-2.sh

@@ -74,8 +74,6 @@ Thu Jan  1 00:00:08 1970 +0000
 EOF
 
 mcron -s cron/foo.guile > output
-diff expected output \
-    || skip_ 'The -s option is not fully functional; 
-this will be fixed with a future version of GNU Guile.'
+diff expected output || fail_ "schedule output with -s is not correct"
 
 Exit 0

tests/schedule.sh

@@ -126,6 +126,6 @@ Thu Jan  1 00:00:10 1970 +0000
 EOF
 
 mcron --schedule=10 > output
-diff expected output || fail_ "schedule output is not correct"
+diff expected output || fail_ "schedule output with --schedule is not correct"
 
 Exit 0