[1.2.X] Refs #11256 -- Extended the annotation field name conflict check to...

[1.2.X] Refs #11256 -- Extended the annotation field name conflict check to cover m2ms and reverse related descriptors as well. This is needed to actually cover the case raised by #14373. Backport of [14116].

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14117 bcc190cf-cafb-0310-a4f2-bffc1f526a37