Add argp & progname modules to fix OSX compile errors

Get argp and progname modules from gnulib instead of depending on the
OS version.

Fixes #1.

Author: alanfalloon

bootstrap.conf

@@ -18,10 +18,12 @@
 
 # gnulib modules used by this package.
 gnulib_modules="
+  argp
   fprintftime
-  parse-datetime
   git-version-gen
   gitlog-to-changelog
+  parse-datetime
+  progname
 "
 
 # Additional xgettext options to use.  Use "\\\newline" to break lines.