Fix build on Python 3.10 (rhbz#1889726).

Backport two fixes:
* https://github.com/NLnetLabs/unbound/commit/e0d426ebb10653a78bf5c4053198f6ac19bfcd3e
* https://github.com/NLnetLabs/unbound/pull/427

diff --git a/libunbound/python/libunbound.i b/libunbound/python/libunbound.i
index a23c45b9c..ab244a6fb 100644
--- a/libunbound/python/libunbound.i
+++ b/libunbound/python/libunbound.i
@@ -916,7 +916,13 @@ int _ub_resolve_async(struct ub_ctx* ctx, char* name, int rrtype, int rrclass, v
       struct cb_data* id;
       id = (struct cb_data*) iddata;
       arglist = Py_BuildValue("(OiO)",id->data,status, SWIG_NewPointerObj(SWIG_as_voidptr(result), SWIGTYPE_p_ub_result, 0 |  0 ));   // Build argument list
+#if PY_MAJOR_VERSION <= 2 || (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION < 9)
+      /* for python before 3.9 */
       fresult = PyEval_CallObject(id->func,arglist);     // Call Python
+#else
+      /* for python 3.9 and newer */
+      fresult = PyObject_Call(id->func,arglist,NULL);
+#endif
       Py_DECREF(id->func);
       Py_DECREF(id->data);
       free(id);
diff --git a/pythonmod/pythonmod.c b/pythonmod/pythonmod.c
index 9006429ef..040ff7051 100644
--- a/pythonmod/pythonmod.c
+++ b/pythonmod/pythonmod.c
@@ -299,7 +299,10 @@ int pythonmod_init(struct module_env* env, int id)
       PyImport_AppendInittab(SWIG_name, (void*)SWIG_init);
 #endif
       Py_Initialize();
+#if PY_MAJOR_VERSION <= 2 || (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION <= 6)
+      /* initthreads only for python 3.6 and older */
       PyEval_InitThreads();
+#endif
       SWIG_init();
       mainthr = PyEval_SaveThread();
    }
@@ -354,6 +357,8 @@ int pythonmod_init(struct module_env* env, int id)
    /* TODO: deallocation of pe->... if an error occurs */
 
    if (PyRun_SimpleFile(script_py, pe->fname) < 0) {
+#if PY_MAJOR_VERSION <= 2 || (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION < 9)
+      /* for python before 3.9 */
       log_err("pythonmod: can't parse Python script %s", pe->fname);
       /* print the error to logs too, run it again */
       fseek(script_py, 0, SEEK_SET);
@@ -369,9 +374,45 @@ int pythonmod_init(struct module_env* env, int id)
       /* ignore the NULL return of _node, it is NULL due to the parse failure
        * that we are expecting */
       (void)PyParser_SimpleParseFile(script_py, pe->fname, Py_file_input);
+#else
+      /* for python 3.9 and newer */
+      char* fstr = NULL;
+      size_t flen = 0;
+      log_err("pythonmod: can't parse Python script %s", pe->fname);
+      /* print the error to logs too, run it again */
+      fseek(script_py, 0, SEEK_END);
+      flen = (size_t)ftell(script_py);
+      fstr = malloc(flen+1);
+      if(!fstr) {
+	      log_err("malloc failure to print parse error");
+	      PyGILState_Release(gil);
+	      fclose(script_py);
+	      return 0;
+      }
+      fseek(script_py, 0, SEEK_SET);
+      if(fread(fstr, flen, 1, script_py) < 1) {
+	      log_err("file read failed to print parse error: %s: %s",
+		pe->fname, strerror(errno));
+	      PyGILState_Release(gil);
+	      fclose(script_py);
+	      free(fstr);
+	      return 0;
+      }
+      fstr[flen] = 0;
+      /* we compile the string, but do not run it, to stop side-effects */
+      /* ignore the NULL return of _node, it is NULL due to the parse failure
+       * that we are expecting */
+      (void)Py_CompileString(fstr, pe->fname, Py_file_input);
+#endif
       log_py_err();
       PyGILState_Release(gil);
       fclose(script_py);
+#if PY_MAJOR_VERSION <= 2 || (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION < 9)
+      /* no cleanup needed for python before 3.9 */
+#else
+      /* cleanup for python 3.9 and newer */
+      free(fstr);
+#endif
       return 0;
    }
 #if PY_MAJOR_VERSION < 3
diff --git a/pythonmod/pythonmod.c b/pythonmod/pythonmod.c
index 040ff70..6e60d02 100644
--- a/pythonmod/pythonmod.c
+++ b/pythonmod/pythonmod.c
@@ -338,7 +338,7 @@ int pythonmod_init(struct module_env* env, int id)
    PyFileObject = PyFile_FromString((char*)pe->fname, "r");
    script_py = PyFile_AsFile(PyFileObject);
 #else
-   script_py = _Py_fopen(pe->fname, "r");
+   script_py = fopen(pe->fname, "r");
 #endif
    if (script_py == NULL)
    {