[1.7.x] Add a useful stacklevel to some RemovedInDjango19Warnings

Backport of b077ba7a from master

django/contrib/gis/db/backends/util.py

@@ -4,6 +4,7 @@ from django.utils.deprecation import RemovedInDjango19Warning
 
 warnings.warn(
     "The django.contrib.gis.db.backends.util module has been renamed. "
-    "Use django.contrib.gis.db.backends.utils instead.", RemovedInDjango19Warning)
+    "Use django.contrib.gis.db.backends.utils instead.",
+    RemovedInDjango19Warning, stacklevel=2)
 
 from django.contrib.gis.db.backends.utils import *  # NOQA

django/db/backends/util.py

@@ -4,6 +4,7 @@ from django.utils.deprecation import RemovedInDjango19Warning
 
 warnings.warn(
     "The django.db.backends.util module has been renamed. "
-    "Use django.db.backends.utils instead.", RemovedInDjango19Warning)
+    "Use django.db.backends.utils instead.", RemovedInDjango19Warning,
+    stacklevel=2)
 
 from django.db.backends.utils import *  # NOQA

django/forms/util.py

@@ -4,6 +4,6 @@ from django.utils.deprecation import RemovedInDjango19Warning
 
 warnings.warn(
     "The django.forms.util module has been renamed. "
-    "Use django.forms.utils instead.", RemovedInDjango19Warning)
+    "Use django.forms.utils instead.", RemovedInDjango19Warning, stacklevel=2)
 
 from django.forms.utils import *  # NOQA

django/utils/tzinfo.py

@@ -12,7 +12,7 @@ from django.utils.encoding import force_str, force_text, DEFAULT_LOCALE_ENCODING
 warnings.warn(
     "django.utils.tzinfo will be removed in Django 1.9. "
     "Use django.utils.timezone instead.",
-    RemovedInDjango19Warning)
+    RemovedInDjango19Warning, stacklevel=2)
 
 
 # Python's doc say: "A tzinfo subclass must have an __init__() method that can