bug #26215: mysql command line client should not strip comments
              from SQL statements
and
  bug #11230: Keeping comments when storing stored procedures

With the introduction of multiline comments support in the command line
client (mysql) in MySQL 4.1, it became impossible to preserve
client-side comments within single SQL statements or stored routines.
This feature was useful for monitoring tools and maintenance.

The patch adds a new option to the command line client
('--enable-comments', '-c') which allows to preserve SQL comments and
send them to the server for single SQL statements, and to keep comments
in the code for stored procedures / functions / triggers.

The patch is a modification of the contributed patch from bug #11230
with the following changes:
- code style changes to conform to the coding guidelines
- changed is_prefix() to my_strnncoll() to detect the DELIMITER
command, since the first one is case-sensitive and not charset-aware
- renamed t/comments-51.* to t/mysql_comments.*
- removed tests for comments in triggers since 5.0 does not have SHOW
CREATE TRIGGER (those tests will be added back in 5.1).

The test cases are only for bug #11230. No automated test case for bug
#26215 is possible due to the test suite deficiencies (though the cases
from the bug report were tested manually).