AND REMAIN A TEMP TABLE

Analysis:
=========
ALTER TABLE, CONVERT TO CHARACTER SET operation remains
ineffective if
a) Table contains only numerical data types.
b) Algorithm used is INPLACE.
Also the temporary '.frm' file created during the
operation is not cleaned up.

For the above ALTER TABLE operation, appropriate handler
flag is not set, resulting in a no-op. Hence the operation
remains ineffective and the CHARACTER SET is not altered.
Also the temporary '.frm' file created was not cleaned up
at the end of no-op.

Note: The above operation for tables having character
data types reports an appropriate error.

Fix:
===
a) Removed the ALTER_CONVERT flag used by parser
   to flag the CONVERT TO CHARACTER SET operation
   since it has similar use as that of ALTER_OPTIONS.
b) ALTER_OPTIONS is now used to indicate the CONVERT
   TO CHARACTER SET operation as well.
c) Added code to clean up the temporary '.frm' file
   created during no-op.