dojump: Fix gcc.dg/torture/pr91323.c for aarch64 targets

PR91323 was fixed for x86 and sparc in target code, but aarch64
instead relies on the target-independent comparison splitters.
Since LTGT is an unordered-signalling operation, we should split
it into unordered-signalling operations for any input that could
be NaN, not just inputs that could be signalling NaNs.

2020-01-27  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* dojump.c (split_comparison): Use HONOR_NANS rather than
	HONOR_SNANS when splitting LTGT.

gcc/ChangeLog

+2020-01-27  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* dojump.c (split_comparison): Use HONOR_NANS rather than
+	HONOR_SNANS when splitting LTGT.
+
 2020-01-27  Martin Liska  <mliska@suse.cz>
 
 	PR driver/91220

gcc/dojump.c

@@ -897,7 +897,7 @@ split_comparison (enum rtx_code code, machine_mode mode,
       return false;
     case LTGT:
       /* Do not turn a trapping comparison into a non-trapping one.  */
-      if (HONOR_SNANS (mode))
+      if (HONOR_NANS (mode))
 	{
           *code1 = LT;
           *code2 = GT;