RFR 8187281 : Remove @intermittent from OnExitTest

[Roger Riggs]

Please review the removal of the @intermittent keyword from OnExitTest.
The failure has not occurred since it was fixed on 9/21.

--- old/test/jdk/java/lang/ProcessHandle/OnExitTest.java	2017-11-06 16:45:40.762305867 -0500
+++ new/test/jdk/java/lang/ProcessHandle/OnExitTest.java	2017-11-06 16:45:40.206333294 -0500
@@ -40,7 +40,6 @@
  
  /*
   * @test
- * @key intermittent
   * @library /test/lib
   * @build jdk.test.lib.Utils
   * @run testng OnExitTest

Issue: https://bugs.openjdk.java.net/browse/JDK-8187281

Thanks, Roger