PR with static-jdk launcher

[Magnus Ihse Bursie]

Hi,

I just wanted to let you know that there is now a PR with an initial 
implementation of a static java launcher:

https://github.com/openjdk/jdk/pull/20837

Some noteworthy limitations:

1) Support for hiding local symbols in static libraries are not yet 
implemented. This mean that there are symbol clashes between some 
libraries. As a result, I have temporarily disabled a few libraries. 
This in turn means that the native code is not complete, so not all JDK 
functionality is present. How much is missing depends on which platform 
you run.

2) Only the java launcher is present, no other JDK launchers (including 
javac) are present. This means that it is not possible to run JTReg 
tests. I have an idea on how to address this in the future.

3) On Windows, changes need to be done in the launcher code; similar to 
what has been done for Linux and macOS. As a result of this, the static 
launcher builds just fine, but crashes at startup. I don't think it is 
hard to fix, but I have not prioritized this. The reason is that the 
inclusion of a working static launcher for macOS and Linux will help the 
Hermetic Java project along, and the Windows launcher can be fixed in 
the meantime.

4) This is not tested on AIX nor any other platforms apart from Linux, 
macOS and Windows. It is tested with both gcc and clang on Linux.

5) There are still a lot of untidy and badly structured code surrounding 
static libraries. I hope to address some of this mess as follow-up work.

6) This PR does not address the issue that all native files are compiled 
twice. That is a completely orthogonal problem to this.

/Magnus