ctypes triggers selinux execmem denial

https://bugzilla.redhat.com/show_bug.cgi?id=488396

fix issue #168. Thanks!

gunicorn/util.py

@@ -4,7 +4,13 @@
 # See the NOTICE for more information.
 
 
-import ctypes
+try:
+    import ctypes
+except MemoryError:
+    # selinux execmem denial
+    # https://bugzilla.redhat.com/show_bug.cgi?id=488396
+    ctypes = None
+
 import fcntl
 import os
 import pkg_resources
@@ -87,6 +93,8 @@ def set_owner_process(uid,gid):
         try:
             os.setgid(gid)
         except OverflowError:
+            if not ctypes:
+                raise
             # versions of python < 2.6.2 don't manage unsigned int for
             # groups like on osx or fedora
             os.setgid(-ctypes.c_int(-gid).value)
@@ -98,6 +106,8 @@ def chown(path, uid, gid):
     try:
         os.chown(path, uid, gid)
     except OverflowError:
+        if not ctypes:
+            raise
         os.chown(path, uid, -ctypes.c_int(-gid).value)