Use that instead of checking HAVE_PNG manually. Change-Id: I70876982c2506bee1173341fa100f5fae2ae4302 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/58709 Maintainer: Gabe Black <gabe.black@gmail.com> Reviewed-by: Yu-hsin Wang <yuhsingw@google.com> Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com> Tested-by: kokoro <noreply+kokoro@google.com>