RFR(XS) 8054547: Re-enable warning for incompatible java launcher

[Zhengyu Gu]

This is a small change to re-enable incompatible launcher warning. The 
warning was disabled to avoid the unexpected warning message to disrupt 
tests, while launcher and hotspot changes are out of sync. Now, launcher 
change has reached promotion build, and they are in sync again, so the 
warning should be re-enabled.

Bug:https://bugs.openjdk.java.net/browse/JDK-8054547 
<https://bugs.openjdk.java.net/browse/JDK-8054547>
Webrev: http://cr.openjdk.java.net/~zgu/8054547/webrev.00/ 
<http://cr.openjdk.java.net/%7Ezgu/8054547/webrev.00/>

Test:
   Dropped hotspot build to JDK9 b25, and ran "java 
-XX:NativeMemoryTracking=detail -version", warning message was displayed.

./jdk1.9.0/bin/java -XX:NativeMemoryTracking=detail -version
Java HotSpot(TM) Server VM warning: Native Memory Tracking did not setup 
properly, using wrong launcher?
java version "1.9.0-ea"
Java(TM) SE Runtime Environment (build 1.9.0-ea-b25)
Java HotSpot(TM) Server VM (build 1.9.0-fastdebug-internal, mixed mode)

Thanks,

-Zhengyu