Log Message:
Update to 1.4.13. Set LICENSE (gnu-gpl-v3).

* Noteworthy changes in Version 1.4.13 (2009-04-01) [stable]
  Released by Eric Blake, based on git version 1.4.12.*

** The manual is now distributed under the terms of FDL 1.3.

** The `divert' and `undivert' builtins have been made more efficient
   when using temporary files for large diversions.

** The `translit' builtin has been made more efficient when the second
   argument is short.

** The input engine has been optimized for faster processing.

** The command line option `--debugfile', introduced in 1.4.7, now
   treats its argument as optional, in order to allow setting the debug
   output back to stderr when used without an argument; and order is now
   significant with respect to command line files.  You must therefore use
   `m4 --debugfile=trace file', not `m4 file --debugfile trace'.  This
   change does not affect the deprecated `-o'/`--error-output' option.

** The `syscmd' and `esyscmd' builtins can be configured to use an
   alternate shell, via the new `configure' option `--with-syscmd-shell'.

** A number of portability improvements inherited from gnulib.