re PR fortran/89103 (Allow blank format items in format strings)

re PR fortran/89103 (Allow blank format items in format strings)

2019-06-19  Jim MacArthur  <jim.macarthur@codethink.co.uk>
	    Mark Eggleston  <mark.eggleston@codethink.com>

	PR fortran/89103
	* gfortran.texi: Add -fdec-blank-format-item
	* invoke.texi: Add option to list of options.
	* invoke.texi: Add to section on Commas in FORMAT specifications.
	* io.c (check_format): At FMT_RPAREN goto finished if
	-fdec-blank-format-item otherwise set error string.
	* lang.opt: Add new option.
	* options.c (set_dec_flags): Add SET_BITFLAG for
	flag_dec_format_defaults.

	* gfortran.dg/dec_format_empty_item_1.f: New test.
	* gfortran.dg/dec_format_empty_item_2.f: New test.
	* gfortran.dg/dec_format_empty_item_3.f: New test.

Co-Authored-By: Mark Eggleston <mark.eggleston@codethink.com>
From-SVN: r272467