X87: disable the regress-undefined-nan test case for x87.

test/mjsunit/mjsunit.status

Index: test/mjsunit/mjsunit.status
diff --git a/test/mjsunit/mjsunit.status b/test/mjsunit/mjsunit.status
index ec25a58f707f0991fd50ded99d312cf828055b58..b776894f617aee8115e86953b15a0cb928aef5c3 100644
--- a/test/mjsunit/mjsunit.status
+++ b/test/mjsunit/mjsunit.status
@@ -577,6 +577,12 @@
 }],  # 'arch == mips'
 
 ##############################################################################
+['arch == x87', {
+  # Turbofan will hit the known issue that x87 changes sNaN to qNaN by default.
+  'regress/regress-undefined-nan': [SKIP],
+}],  # 'arch == x87'
+
+##############################################################################
 ['arch == mips64el or arch == mips64', {
 
   # Slow tests which times out in debug mode.