OnError and OnOutOfMemoryError checks

The JVM options OnError and OnOutOfMemoryError enable executing arbitrary commands if the JVM encounters a fatal error (OnError) or an OutOfMemoryError (OnOutOfMemoryError). However, by default, Elasticsearch system call filters (seccomp) are enabled and these filters prevent forking. Thus, using OnError or OnOutOfMemoryError and system call filters are incompatible. The OnError and OnOutOfMemoryError checks prevent Elasticsearch from starting if either of these JVM options are used and system call filters are enabled. This check is always enforced. To pass this check do not enable OnError nor OnOutOfMemoryError; instead, upgrade to Java 8u92 and use the JVM flag ExitOnOutOfMemoryError. While this does not have the full capabilities of OnError nor OnOutOfMemoryError, arbitrary forking will not be supported with seccomp enabled.