MySQL 5.5.17

# Bugs Fixed :
* InnoDB Storage Engine: This fix improves the performance of instrumentation code for InnoDB buffer pool operations.
* InnoDB Storage Engine: Data from BLOB columns could be lost if the server crashed at a precise moment when other columns were being updated in an InnoDB table.
* InnoDB Storage Engine: Lookups using secondary indexes could give incorrect matches under a specific set of conditions. The conditions involve an index defined on a column prefix, for a BLOB or other long column stored outside the index page, with a table using the Barracuda file format.
* InnoDB Storage Engine: This fix corrects cases where the MySQL server could hang or abort with a long semaphore wait message. (This is a different issue than when these symptoms occurred during a CHECK TABLE statement.)
* Internal conversion of zero to binary and back could yield a result with incorrect precision.
* Valgrind warnings generated by filesort operations were fixed.
* mysqld_safe did not properly check for an already running instance of mysqld.
* The help message for mysql_install_db did not indicate that it supports the --defaults-file, --defaults-extra-file and --no-defaults options.
* An assertion designed to detect zero-length sort keys also was raised when the entire key set fit in memory.
* myisampack could create corrupt FULLTEXT indexes when compressing tables.
* A linking problem prevented the FEDERATED storage engine plugin from loading.