Issue #7736: Release the GIL around calls to opendir() and closedir()
in the posix module.  Patch by Marcin Bachry.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index ce625b4..1080c7e 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -2580,11 +2580,16 @@
       oname = PyBytes_FromString(".");
     }
     name = PyBytes_AsString(oname);
-    if ((dirp = opendir(name)) == NULL) {
+    Py_BEGIN_ALLOW_THREADS
+    dirp = opendir(name);
+    Py_END_ALLOW_THREADS
+    if (dirp == NULL) {
         return posix_error_with_allocated_filename(oname);
     }
     if ((d = PyList_New(0)) == NULL) {
+        Py_BEGIN_ALLOW_THREADS
         closedir(dirp);
+        Py_END_ALLOW_THREADS
         Py_DECREF(oname);
         return NULL;
     }
@@ -2597,7 +2602,9 @@
             if (errno == 0) {
                 break;
             } else {
+                Py_BEGIN_ALLOW_THREADS
                 closedir(dirp);
+                Py_END_ALLOW_THREADS
                 Py_DECREF(d);
                 return posix_error_with_allocated_filename(oname);
             }
@@ -2621,7 +2628,9 @@
         }
         Py_DECREF(v);
     }
+    Py_BEGIN_ALLOW_THREADS
     closedir(dirp);
+    Py_END_ALLOW_THREADS
     Py_DECREF(oname);
 
     return d;