D.2.9 Modifications de la version 3.22.18

• Fixes a fatal problem in 3.22.17 on Linux; After shutdown all threads didn't die properly.
• Added option -O flush-time=# to mysqld. This is mostly useful on Win32 and tells how often MySQL should close all unused tables and flush all updated tables to disk.
• Fixed problem that a VARCHAR column compared with CHAR column didn't use keys efficiently.