add yet-to-be tested support for innodb_flush_method=allsync
add yet-to-be tested support for innodb_flush_method=allsync
sdgdsffdsfff/google-mysql-tools,vincentor/google-mysql-tools,dbarobin/google-mysql-tools,dbarobin/google-mysql-tools,sdgdsffdsfff/google-mysql-tools,vincentor/google-mysql-tools