Fix usage of secure_getenv with glibc 2.17.

Fix usage of secure_getenv with glibc 2.17.

See http://sourceware.org/glibc/wiki/Tips_and_Tricks/secure_getenv

2012-10-06  Janne Blomqvist  <jb@gcc.gnu.org>

	* configure.ac: Check for presence of secure_getenv.
	* libgfortran.h: Use HAVE_SECURE_GETENV.
	* Makefile.in: Regenerated.
	* aclocal.m4: Regenerated.
	* config.h.in: Regenerated.
	* configure: Regenerated.

From-SVN: r192169