RFR: JDK-8242629 Remove references to deprecated java.util.Observer and Observable

[Magnus Ihse Bursie]

As a first step towards fixing deprecation warnings in SA, all the 
references (200+) to the deprecated java.util.Observer and Observable 
needs to be fixed, otherwise all other changes will drown in this one.

This solution is the result of the preceding discussions in 
serviceability-dev. That means that most of the change consists of 
adding an explicit import like this:

import sun.jvm.hotspot.utilities.Observable;
import sun.jvm.hotspot.utilities.Observer;

to override the general java.util.* import that was already present in 
all (or almost all) files, and make sun.jvm.hotspot.utilities.Observable 
and Observer extend the java.util versions but with deprecation warnings 
disabled.

It turned out however, that this simplest approach did not work fully. 
Since the interface java.util.Observer had the single method "void 
update(java.util.Observable o, Object arg)" it did not help to create a 
new interface sun.jvm.hotspot.utilities.Observer that extended 
java.util.Observer. I did not observe this issue in my PoC webrev that I 
posted during the discussion. :-(

Instead, for Observer, I had just created a new interface with the same 
method, but that uses sun.jvm.hotspot.utilities.Observable instead of 
java.util.Observable.

The end effect is the same -- the only change needed to most files is an 
added import, we get rid of the deprecation warnings, and we did not 
have to copy any significant amount of code from java.util.

I now hope this is acceptable by all.

Bug: https://bugs.openjdk.java.net/browse/JDK-8242629
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8242629-fix-SA-Observer/webrev.01

(When reading the patch, I recommend looking at the patch file 
http://cr.openjdk.java.net/~ihse/JDK-8242629-fix-SA-Observer/webrev.01/open.patch 
instead of individually checking the files in the webrev.)

/Magnus