Fixed #11487: pass long strings to Oracle as CLOB rather than NCLOB to prevent...

Fixed #11487: pass long strings to Oracle as CLOB rather than NCLOB to prevent an encoding bug that occurs in some installations. Backport of [11285] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@11286 bcc190cf-cafb-0310-a4f2-bffc1f526a37