tests/Makefile: Add more dependencies for test-timed-average

'make check' failed to compile the test case for mingw because of
undefined references. Pull in a few more dependencies so that it builds.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
