cutils: Introduce bundle mechanism

Developers often run QEMU without installing. The bundle mechanism
allows to look up files which should be present in installation even in
such a situation.

It is a general mechanism and can find any files in the installation
tree. The build tree will have a new directory, qemu-bundle, to
represent what files the installation tree would have for reference by
the executables.

Note that it abandons compatibility with Windows older than 8. The
extended support for the prior version, 7 ended more than 2 years ago,
and it is unlikely that someone would like to run the latest QEMU on
such an old system.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220624145039.49929-3-akihiko.odaki@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>