PR70117, ppc long double isinf

PR70117, ppc long double isinf

gcc/
	PR target/70117
	* builtins.c (fold_builtin_classify): For IBM extended precision,
	look at just the high-order double to test for NaN.
	(fold_builtin_interclass_mathfn): Similarly for Inf.  For isnormal
	test just the high double for Inf but both doubles for subnormal
	limit.
gcc/testsuite/
	* gcc.target/powerpc/pr70117.c: New.

From-SVN: r234821