builtins.c (expand_errno_check): Assume that flag_errno_math and HONOR_NANS have...

builtins.c (expand_errno_check): Assume that flag_errno_math and HONOR_NANS have been tested before calling here.

	* builtins.c (expand_errno_check): Assume that flag_errno_math
	and HONOR_NANS have been tested before calling here.  Only try
	to set errno ourselves if the decl can't throw an exception.
	(expand_builtin_mathfn): Move the code to stabilize the arg
	after the main switch, so that that its only done when needed.
	BUILT_IN_SQRT{,F,L} doesn't set errno if its arg is nonnegative.
	Don't modify the original expr when stabilizing the argument.
	(expand_builtin_mathfn_2): Likewise, move the code to stabilize
	the args after the main switch, and don't modify the orginal exp.

From-SVN: r68217