[PATCH] segfault after (re-)moving audit log file

if an external program will move or remove the audit log, a segmentation fault will occur. this error will not happen, if the audit log file exist while mysql is started. if flush logs is executed after file has been moved but before stop+start of audit is triggered (via setting the file path or setting audit=OFF and audit=ON, see logrotate config), the probability of getting a segfault will be reduced.

problem will occur with audit plugin (file rotation disabled) + mysql 5.6 + ubuntu 14.04 on git commit cc84ac3be41d9d6ac480d55449d5bf4e324cca10

gdb output: http://pastebin.com/ccs2Fug7
logrotate script: http://pastebin.com/CnLANyEm
mysql error log: http://pastebin.com/P51NsFxs

my naive solution would be to call stop_logging/start_logging on rotate() if file rotations are set to 0. this will trigger the needed reopen of the logfile