* fold-const.c (build_range_check): If !in_p and recursive call
	fails, exit immediately.  If high - low overflows and etype is
	a signed type, retry with unsigned etype.
	(merge_ranges): If !in0_p and !in1_p, handle even range2 adjacent
	to range1 at TYPE_MAX_VALUE and TYPE_MIN_VALUE.

	* gcc.dg/range-test-1.c: New test.
	* g++.dg/opt/range-test-1.C: New test.

From-SVN: r83369