re PR c/56724 (sub-optimal location in error)

re PR c/56724 (sub-optimal location in error)

	PR c/56724
	* c-typeck.c (convert_arguments): Get location of a parameter.  Change
	error and warning calls to error_at and warning_at.  Pass location of
	a parameter to it.  Call warning_at with OPT_Wtraditional_conversion.
	(convert_for_assignment): Add parameter to WARN_FOR_ASSIGNMENT and
	WARN_FOR_QUALIFIERS.  Pass expr_loc to those.

	* gcc.dg/pr56724-1.c: New test.
	* gcc.dg/pr56724-2.c: New test.
	* gcc.dg/wtr-conversion-1.c: Use -Wtraditional-conversion instead of
	-Wtraditional.
	* gcc.dg/dfp/wtr-conversion-1.c: Likewise.

From-SVN: r210980