[jdk20] Integrated: 8298459: Fix msys2 linking and handling out of tree build directory for source zip creation

[Christoph Langer]

On Fri, 9 Dec 2022 11:26:46 GMT, Christoph Langer <clanger at openjdk.org> wrote:

> This PR fixes two issues.
> 
> In ZipSource.gmk we don't account for the possibility of the build directory or `$(SUPPORT_OUTPUTDIR)` not being in the source directory tree (`$(TOPDIR)`).
> It doesn't manifest in a build error though since link-file-relative will then fall back to absolute linking. But it results in awkward paths.
> 
> Furthermore, there's a lurking issue in msys2 builds on Windows. There, ln would create deep copies of a file system tree instead of linking. If the file system to be linked contains long paths, it could result in 'File name too long' errors, like can be seen [here](https://github.com/gdams/jdk11u-dev/actions/runs/3563481453/jobs/5986319107). We can avoid this by calling Windows mklink to create a file system junction. Presumably that would also help build performance (though not verified).

This pull request has now been integrated.

Changeset: d624debe
Author:    Christoph Langer <clanger at openjdk.org>
URL:       https://git.openjdk.org/jdk20/commit/d624debe23f60d778d7be43f28d06e9454057217
Stats:     27 lines in 2 files changed: 20 ins; 0 del; 7 mod

8298459: Fix msys2 linking and handling out of tree build directory for source zip creation

Reviewed-by: erikj

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PR: https://git.openjdk.org/jdk20/pull/9