Set PATH_MAX to some constant in case it is not defined in system
headers.

2013-10-06  Jose E. Marchesi  <jemarch@gnu.org>

	* basicdefs.h (PATH_MAX): Defined to some constant in case it is
	not defined by system headers.
	* sed/utils.c: Do not include pathmax.h anymore.
	* bootstrap.conf (gnulib_modules): Do not use the gnulib module
	pathmax.