Bryan Donlan authored May 03, 2017 and Brad King committed May 04, 2017

OpenJDK 9 early access builds use a version string of "9-ea", and
locally built installations use "9-internal", neither of which is
currently accepted by the FindJava macro.  Map those versions to "1.9".
If the final released version is "9.0" the version interpretation could
be changed to match at that time.