Skip tests using pthreads on Windows

Note: They were causing hard exits of Python, not exceptions, this
      is something that will have to be fixed in the future

test_atomic_add.py

@@ -8,6 +8,7 @@ from llvm.ee import *
 from llvm_cbuilder import *
 import llvm_cbuilder.shortnames as C
 import unittest, logging
+import sys
 
 # logging.basicConfig(level=logging.DEBUG)
 
@@ -66,6 +67,7 @@ def gen_test_pthread(mod):
     return cb.function
 
 class TestAtomicAdd(unittest.TestCase):
+    @unittest.skipIf(sys.platform == 'win32', "test uses pthreads, not supported on Windows")
     def test_atomic_add(self):
         mod = Module.new(__name__)
         # add pthread functions

test_atomic_cmpxchg.py

@@ -8,6 +8,7 @@ from llvm.ee import *
 from llvm_cbuilder import *
 import llvm_cbuilder.shortnames as C
 import unittest, logging
+import sys
 
 # logging.basicConfig(level=logging.DEBUG)
 
@@ -71,6 +72,7 @@ def gen_test_pthread(mod):
     return cb.function
 
 class TestAtomicCmpXchg(unittest.TestCase):
+    @unittest.skipIf(sys.platform == 'win32', "test uses pthreads, not supported on Windows")
     def test_atomic_cmpxchg(self):
         mod = Module.new(__name__)
         # add pthread functions

test_pthread.py

@@ -4,6 +4,7 @@ from llvm.ee import *
 from llvm_cbuilder import *
 import llvm_cbuilder.shortnames as C
 import unittest, logging
+import sys
 
 # logging.basicConfig(level=logging.DEBUG)
 
@@ -50,6 +51,7 @@ def gen_test_pthread(mod):
     return cb.function
 
 class TestPThread(unittest.TestCase):
+    @unittest.skipIf(sys.platform == 'win32', "pthreads not supported on Windows")
     def test_pthread(self):
         mod = Module.new(__name__)
         # add pthread functions