8154956: Module system implementation refresh (4/2016)

[Alan Bateman]

There have several changes in jake that we need to bring into jdk9/dev. 
The main changes are:

1. The policy described in JEP 261 for the root modules to resolve when 
compiling code in the unnamed module or where the main class is loaded 
from the class file. This is a disruptive change and we need to get 
through the transition.

Related is a new token `ALL-DEFAULT` that can be specified to `-addmods` 
to resolve the same roots when the initial module is a named module. 
This will eventually replace `ALL-SYSTEM` but we can't remove that just 
yet. The launchers for javac, javadoc, jlink and a few other tools that 
load arbitrary code in unnamed modules are now compiled with this option.

2. The transition to the new form of -Xpatch. This is mostly changes in 
hotspot but there are changes in other repos too to drop or replace the 
old form of -Xpatch (boot cycle builds for example).

3. Removal of the old form of -XaddExports and -XaddReads. This has 
build + test changes.

4. The second phase of integrity hashing. With this phase then the build 
records in java.base the hashes of the non-upgradeable modules. This 
prevents accidental linking of standard/JDK modules from different JDK 
builds. The jar and jmod tools have updated options to support this.

5. Peter Levart's patch to replace the internal WeakSet in jlr.Module 
with a WeakKeyPair.

6. Updates to jlink option handling. The reason this went into jdk9/dev 
is that it is disruptive to FX packager and it's hard to coordinate with 
FX when it's a separate forest. The packager class that Chris Bensen has 
added to jlink will allows us to iterate on jlink with reduced risk of 
breaking FX.

There are several small bug fixes and clean-ups in several areas, we'll 
have a lot more of these for the next update.

One other thing to mention is that we've bumped the required version of 
jtreg as jtreg relies on-Xpatch to add test cases into modules and so it 
needed to be updated too.

The webrevs, all repos are here:
   http://cr.openjdk.java.net/~alanb/8154956/1/

There are a couple of files in the webrevs that we probably won't bring 
to JDK 9 in this update:

i. We have a patch to IDL compiler in the corba repo that needs a more 
extensive fix.
ii. The javadoc change in ModuleFinder as there are still details to 
decide on how modular JARs work as multi-release JARs.

One other point is that the webrevs are against jdk-9+116 for now. I've 
done a test merge + build with the current jdk9/dev forest and there are 
only a few conflicts to fix. I will re-merge + test with jdk9/dev once 
we have agreed the changes for this update.

Finally, just to say that we'll probably continue in jake for a while 
after we get through this update. There are several design issues on the 
JSR issues list that will likely require a few iterations and a bit of 
bake time before we bring them to JDK 9.

-Alan