ExternalProject: Restore support for Xcode with an effective platform
Revert commit cabad8a37f (ExternalProject: Always use $<CONFIG> for
source files, 2023-02-02, v3.27.0-rc1~550^2~3) and restore
Xcode-specific behavior intentionally preserved by commit c111d440ce
(ExternalProject: Express per-config step stamp file paths using CONFIG
genex, 2022-06-08, v3.24.0-rc1~15^2). Unfortunately we still do not
have a test case, so leave a comment to avoid reverting this.
Issue: #23645
Issue: #23652
1 file changed
