The output directory may be the same as the source directory in
the case of an in-source build, but Xcode treats the SYMROOT as
a build directory, and automatically excludes it from Time Machine
backups, which may result in not backing up sources.
Instead we map SYMROOT to an .xcode subdirectory of the output
directory, and then use CONFIGURATION_BUILD_DIR to make sure
the final build targets end up where they used to.
Task-number: QTBUG-52474
Change-Id: I3852ca9088e75ca62fca4c1217b5485175d9436f
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
7c3053b301