RFA: 8067471: Use private static final char[0] for empty Strings

[Lev Priima]

Please approve and push: https://bugs.openjdk.java.net/browse/JDK-8067471
Review for 9: 
http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-January/030749.html
JDK 9 changeset can be smoothly applied by:
~/code/jdk8u-dev/jdk$ (cd ~/code/jdk9/dev/jdk && hg pull -u && hg diff 
--git -r 95f1c90ebb7f  -r c60cf8acabb2) | sh 
~/code/jdk9/dev/common/bin/unshuffle_patch.sh jdk - - | hg patch -

Lev