fix python3 syntax error

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@294355 91177308-0d34-0410-b5e6-96231b3b80d8

test/support/filesystem_dynamic_test_helper.py

@@ -75,7 +75,7 @@ def create_fifo(source):
 
 
 def create_socket(source):
-    mode = 0600|stat.S_IFSOCK
+    mode = 0o600 | stat.S_IFSOCK
     os.mknod(sanitize(source), mode)