re PR fortran/82143 (add a -fdefault-real-16 flag)

re PR fortran/82143 (add a -fdefault-real-16 flag)

2017-09-23  Janus Weil  <janus@gcc.gnu.org>

	PR fortran/82143
	* lang.opt: Add the options -fdefault-real-10 and -fdefault-real-16.
	Rename flag_default_real to flag_default_real_8.
	* invoke.texi: Add documentation.
	* module.c (use_iso_fortran_env_module): flag_default_real is renamed.
	* trans-types.c (gfc_init_kinds): Implement the flags
	-fdefault-real-10 and -fdefault-real-16. Make -fdefault-double-8 work
	without -fdefault-real-8.

2017-09-23  Janus Weil  <janus@gcc.gnu.org>

	PR fortran/82143
	* gfortran.dg/promotion_3.f90: New test case.
	* gfortran.dg/promotion_4.f90: New test case.

From-SVN: r253117