LOWER_CASE_TABLE_NAMES=2

ANALYSIS:
=========
Consider a server started with lower_case_table_names=2 and
a table with table name in uppercase is created. Certain
privileges on the table are assigned to an user. Connecting
to the server using that user and executing SHOW TABLES
does not display the table with uppercase table name.

With lower_case_table_names set to 2, table and database
names are stored on disk using the lettercase specified in
the CREATE TABLE or CREATE DATABASE statement, but are
converted to lowercase on lookup.

With lower_case_table_names set to 2, GRANT on a table
with uppercase table name will store the user name and
table name information in lowercase in the grant tables.
While executing SHOW TABLES, we fetch table names from
the .frm files in file system.

As the table name is in uppercase and the table name
stored in grant tables is in lowercase, the access check
fails and the table name is not displayed in the result set.

FIX:
====
Use lowercase table name to perform ACL check when
SHOW TABLES is run with lower_case_table_names=2.

Change-Id: Iad60d07aa8222670220be4c22deeba7027966909