Use server core dumping instead of process freeze in gdb

[MEXAHOTABOP]

almost any modern database have some kind of bin log/transaction log, what make possible to restore working state from snapshot or delayed slave replication, so this must be relevantly safe to use since he just need to rollback only some from transactions related to server where crash occurred to prevent instant re-arise

also information about crash will be fully saved since core dump contain full dump of allocated memory, process state and registers