RFR: 8325963: Clean up NativeCompilation.gmk and its newly created parts [v3]

[Magnus Ihse Bursie]

> This is a follow-up to [JDK-8325877](https://bugs.openjdk.org/browse/JDK-8325877). I was careful in that bug not to change order of any lines, only split up the original file into parts.
> 
> In this PR, I use the new structure to improve the design. I collect the functionality into three clearly separate phases, preparation, compilation and linking. I use consistent naming to reveal whether a function just sets up variables, or create output. I simplify and split up a few extra hard to read functions. I move some code around so it is placed more logically.
> 
> It can be hard to convince yourself that the changes are correct if you just look at the end result. I have tried to make small and clear changes in each separate commit, and to explain in the commit title what I am doing. I recommend reviewing this PR [commit by commit](https://github.com/openjdk/jdk/pull/17873/commits).

Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:

  Better fix for "macro"

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/17873/files
  - new: https://git.openjdk.org/jdk/pull/17873/files/449cbae2..17c7690b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17873&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17873&range=01-02

  Stats: 7 lines in 1 file changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/17873.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17873/head:pull/17873

PR: https://git.openjdk.org/jdk/pull/17873