emulators/qemu-utils: Update to 2.9.0

Update emulators/qemu-utils to build at version 2.9.0. Its master port made
the update in r447330.

Reported by: pkg-fallout
Reviewed by: sbruno
Approved by: sbruno (ports)
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D11915