Issue: #25576

Code extracted from:

    https://github.com/madler/zlib.git

at commit 04f42ceca40f73e2978b50e93806c2a18c1281fc (v1.2.13).

# By zlib upstream
* upstream-zlib:
  zlib 2022-10-12 (04f42cec)

22a5252 Merge branch 'upstream-zlib' into update-zlib
6c2bed5 zlib 2022-10-12 (04f42cec)
e868b19 zlib: Fix 1.2.13 version and date notice

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !9204

Issue: #25650

…ures

Sources that will be scanned for C++ module dependencies need to be
excluded from unity builds.  We need to compute compile features in
order to know which sources will be scanned.  Unity build and PCH
sources can be added afterward without changing the compile features.

This re-implements commit 76b5383 (cmGlobalGenerator: add unity
sources after computing target compile features, 2024-01-01,
v3.28.2~17^2~1) using a simpler approach that also preserves support for
PCH with Unity builds.

Issue: #25650
Co-authored-by: Ben Boeckel <ben.boeckel@kitware.com>

Replace commit 76b5383 (cmGlobalGenerator: add unity sources after
computing target compile features, 2024-01-01, v3.28.2~17^2~1) with an
alternative change.  This merge commit resolves conflicts such that
future `git blame` calls will follow the second parent for the relevant
lines and pretend the replaced commit never existed.

Fixes: #25650

30829da Unity: Clarify source comments on unity build transformation
87bf1c6 Merge branch 'unity-after-compile-features' into restore-pch-with-unity
df08c37 cmGlobalGenerator: Add unity/pch sources after computing compile features
004c3c3 Tests: Add case covering PCH in a unity build

Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Acked-by: Ben Boeckel <ben.boeckel@kitware.com>
Merge-request: !9215