Always pass 0 or option number to gfc_warning*.

Always pass 0 or option number to gfc_warning*.

Similar to the issue with fatal_error that I fixed in
<https://gcc.gnu.org/ml/gcc-patches/2015-01/msg02690.html>, the
overloads of gfc_warning and gfc_warning_now (with and without a first
argument for an option number) also break gcc.pot regeneration because
xgettext expects the translated string argument to be in a fixed
position for a given function name.  This patch applies the
corresponding fix of always passing a first argument (option number or
0), just like the core diagnostic functions warning and warning_at,
and removing the problem overloads without it.

Bootstrapped with no regressions on x86_64-unknown-linux-gnu.

	* error.c (gfc_warning (const char *, ...), gfc_warning_now (const
	char *, ...)): Remove functions.
	* gfortran.h (gfc_warning (const char *, ...), gfc_warning_now
	(const char *, ...)): Remove declarations.
	* arith.c, check.c, data.c, decl.c, frontend-passes.c,
	interface.c, intrinsic.c, io.c, matchexp.c, module.c, openmp.c,
	options.c, parse.c, primary.c, resolve.c, scanner.c, symbol.c,
	trans-common.c, trans-const.c, trans-stmt.c: All callers of
	gfc_warning and gfc_warning_now changed to pass 0 or option number
	as first argument.

From-SVN: r220313