RFR: 8330261: Clean up linking steps [v4]

[Magnus Ihse Bursie]

On Mon, 15 Apr 2024 14:21:08 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> Instead of executing code directly in Link.gmk, we set variables that are then evaluated to get the code we want. This is non-transparent and makes it unnecessarily hard to work with the linking code base. 
>> 
>> This PR also contains some additional code cleanup/fixes.
>
> Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:
> 
>   MACOSX_CODESIGN_MODE was not always properly set

It turned out that the MT step failed on Windows, due to the special combination of `"`, `,` and `#`. I tried messing around a bit, but failed to find a solution for all three at the same time. Since the important part of this PR is to get the non-Microsoft linking steps cleaned up, I reverted that part for the time being. 

I have opened [JDK-8330341](https://bugs.openjdk.org/browse/JDK-8330341) to fix ExecuteWithLog. After that is done, we can take another stab at the MT command line.

Now it should work properly. Sorry for the mess. :-(

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PR Comment: https://git.openjdk.org/jdk/pull/18783#issuecomment-2058520681
PR Comment: https://git.openjdk.org/jdk/pull/18783#issuecomment-2058682564