The `CONFIGURATION_BUILD_DIR` value in the Xcode project file specifies
where to place the library artifact.  For object libraries we've used
the `Objects-normal` directory to hide away the `.a` that we otherwise
cannot stop Xcode from producing.  The parent of this directory is also
specific to the target and does not vary with Xcode's sanitizer
features, so move the artifact there.

Issue: #16289