Reduce fallout for avr.

Reduce fallout for avr.

	* lib/target-supports.exp
	(check_effective_target_keeps_null_pointer_checks): No more
	special-case avr.
	* gcc.dg/tree-ssa/pr21086.c (dg-final): Special-case avr.
	* gcc.dg/ifcvt-4.c: Skip avr.
	* gcc.dg/pr53037-1.c: Dito.
	* gcc.dg/pr53037-2.c: Dito.
	* gcc.dg/pr53037-3.c: Dito.
	* gcc.dg/pr63387-2.c: Dito.
	* gcc.dg/pr63387.c: Dito.
	* gcc.dg/sancov/cmp0.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-1.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-10.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-11.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-1b.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-2.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-3.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-4.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-5.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-6.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-7.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-8.c: Dito.
	* gcc.dg/tree-ssa/loop-interchange-9.c: Dito.
	* gcc.dg/tree-ssa/pr82059.c: Dito.
	* gcc.c-torture/execute/pr70460.c: Dito.

From-SVN: r257328