Fix for BUG#4375 "Windows specific directories are copied during
replication": in the Windows version of my_dir(), do not show hidden
or system files which Windows sometimes creates in the root directory
of drive (like RECYCLER and SYSTEM VOLUME INFORMATION directories) (so
this problem showed up only when the datadir was the root dir of a
drive).
This will make SHOW DATABASES display better, and will do no harm to
MySQL. For example, DROP DATABASE will not miss some files, as MySQL
creates no hidden or system files.
"SHOW TABLE STATUS very slow w/large number of tables"
Replaced old algorithm which were used in my_dir() and stored
all information about directory entries in one chunk of memory
with new one which stores file names and MY_STAT structures in
separate memroot, so now we don't need to copy this data during
reallocation of dir_entry array.
mysql_server_init() now returns error code if something went wrong (Bug #2062)
Don't use my_fopen() when reading symlink information as this may cause problems when a lot of files are opened.
Free thread keys with pthread_key_delete() instead of relying on automatic free. (Bug #2062)
Fixed bug in UNION statement with alias '*'. (Bug #1249)
Fixed a bug in DELETE ... ORDER BY ... LIMIT where the rows where not deleted in the proper order. (Bug #1024).
FOUND_ROWS() could return incorrect number of rows after a query with an impossible WHERE condition.
HOW DATABASES doesn't anymore show .sym files (on windows) that doesn't point to a valid directory. (Bug #1385)
