is allowed on views (not documented, broken)".

Remove support of ALTER TABLE RENAME for views as:
a) this feature was not documented,
c) does not add any compatibility with other databases,
b) its implementation doesn't follow metadata locking
   protocol by accessing .FRM without holding any
   metadata lock,
c) its implementation complicates ALTER TABLE's code
   by introducing  yet another separate branch to it.

After this patch one can rename a view by using the
documented way - RENAME TABLE statement.

mysql-test/r/rename.result:
  Adjusted existing test case for bug #14959 "ALTER TABLE isn't
  able to rename a view" after fixing bug #53976: "ALTER TABLE
  RENAME is allowed on views (not documented, broken)".
mysql-test/r/view.result:
  Adjusted test case after removing support for renaming
  of views through ALTER TABLE ... RENAME.
mysql-test/t/rename.test:
  Adjusted existing test case for bug #14959 "ALTER TABLE isn't
  able to rename a view" after fixing bug #53976: "ALTER TABLE
  RENAME is allowed on views (not documented, broken)".
mysql-test/t/view.test:
  Adjusted test case after removing support for renaming
  of views through ALTER TABLE ... RENAME.
sql/sql_table.cc:
  Removed support for ALTER TABLE ... RENAME for views.
  This feature was not properly documented and its
  implementation was not following metadata locking
  protocol.