hg: jdk/submit: 8221723: Avoid storing zero to String.hash

[claes.redestad at oracle.com]

Changeset: 7c576e4d0afa
Author:    redestad
Date:      2019-04-02 11:24 +0200
URL:       http://hg.openjdk.java.net/jdk/submit/rev/7c576e4d0afa

8221723: Avoid storing zero to String.hash
Reviewed-by: shade, prappo, jiangli

! src/java.base/share/classes/java/lang/String.java
! test/micro/org/openjdk/bench/java/lang/StringHashCode.java