Add more status info to error log output in fatal signal handler

In some cases, e.g. when the InnoDB storage engine terminates the server with an abort signal, extra output to the error log could be helpful.

E.g. for innodb related aborts having SHOW ENGINE INNODB STATUS output in the error log might be helpful.

Even more nice would be additional log output in case of segmentation fault or bus error signals, like e.g. always having a final processlist, but there the related data may not necessarily be accessible anymore as it may have been corrupted by invalid memory accesses already ...