This series of patches fix PR61441. This patch makes resulting NaN values
to be quiet NaN for real value operations, irrespective of the flag_signaling_nans
flag. The caller has the responsibility to avoid the operation if flag_signaling_nans
is on.

gcc/
	* real.c (do_add): Make resulting NaN value to be qNaN.
	(do_multiply, do_divide, do_fix_trunc): Same.
	(real_arithmetic, real_ldexp, real_convert): Same.
	(real_isinteger): Updated comment stating it returns false for sNaN.

From-SVN: r231872