[processing] Add 'call' statements to SAGA batch file

Author: backporting[bot]

python/plugins/processing/algs/saga/SagaUtils.py

@@ -109,7 +109,10 @@ def createSagaBatchJobFileFromSagaCommands(commands):
         else:
             pass
         for command in commands:
-            fout.write('saga_cmd ' + command + '\n')
+            if isWindows():
+                fout.write('call saga_cmd ' + command + '\n')
+            else:
+                fout.write('saga_cmd ' + command + '\n')
 
         fout.write('exit')