re PR c/4389 (Improper constant folding)

	PR c/4389
	* tree.c (host_integerp): Ensure that the constant integer is
	representable in a HOST_WIDE_INT or an unsigned HOST_WIDE_INT
	when pos is zero or non-zero respectively.  Clarify comment.
	* c-format.c (check_format_info_recurse): Fix host_integerp
	usage; the pos argument should be zero when assigning to a
	signed HOST_WIDE_INT.

	* gcc.dg/20020219-1.c: New test.

From-SVN: r49914