Alterações na distribuição 3.23.49

Don't give warning for a statement that is only a comment; this is needed for mysqldump --disable-keys to work.

Fixed unlikely caching bug when doing a join without keys. In this case the last used field for a table always returned NULL.
Added options to make LOAD DATA LOCAL INFILE more secure.
MySQL binary release 3.23.48 for Linux contained a new glibc library, which has serious problems under high load and Red Hat 7.2. The 3.23.49 binary release doesn't have this problem.
Fixed shutdown problem on NT.