RFR: JDK-8248488 JDK-8246484 actually broke COMPARE_BUILD

Mon Jun 29 15:50:00 UTC 2020

Unfortunately JDK-8246484, which was supposed to make COMPARE_BUILD 
testing more robust, actually broke COMPARE_BUILD. :-( That patch tries 
to apply the patch with --dry-run at make startup, which was a good 
idea. Unfortunately, it tries to do so as well when running the second 
time in compare mode, and then the patch will fail to apply in --dry-run 
mode, since it is already applied.

Bug: https://bugs.openjdk.java.net/browse/JDK-8248488
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8248488-fix-COMPARE_BUILD/webrev.01

/Magnus