Mark test_sigaction_default as cross platform. NFC (emscripten-core#2…

…0272)

It looks like this test is failing on windows on the emscripten-releases
builder.  Marking it as cross platform to see if it also fails on github
CI on windows.

test/test_core.py

@@ -10,7 +10,6 @@
 import random
 import re
 import shutil
-import signal
 import sys
 import time
 import unittest
@@ -37,6 +36,9 @@
 
 logger = logging.getLogger("test_core")
 
+EM_SIGINT = 2
+EM_SIGABRT = 6
+
 
 def wasm_simd(f):
   @wraps(f)
@@ -6184,14 +6186,15 @@ def test_signals(self):
     self.do_core_test(test_file('test_signals.c'))
 
   @parameterized({
-    'sigint': (signal.SIGINT, 128 + signal.SIGINT, True),
-    'sigabrt': (signal.SIGABRT, 7, False)
+    'sigint': (EM_SIGINT, 128 + EM_SIGINT, True),
+    'sigabrt': (EM_SIGABRT, 7, False)
   })
+  @crossplatform
   def test_sigaction_default(self, signal, exit_code, assert_identical):
     self.set_setting('EXIT_RUNTIME')
     self.do_core_test(
       test_file('test_sigaction_default.c'),
-      args=[str(int(signal))],
+      args=[str(signal)],
       assert_identical=assert_identical,
       assert_returncode=exit_code
     )