I've just applied the latest version of this patch but it's still looking for aarch64/Makefile.inc both during a "make buildworld" and a "make" in usr.sbin/bhyve on my Ampere system:
bcran@gluon:~/src/freebsd/usr.sbin/bhyve % make make: "/home/bcran/src/freebsd/usr.sbin/bhyve/Makefile" line 68: Could not find aarch64/Makefile.inc make: Fatal errors encountered -- cannot continue make: stopped in /home/bcran/src/freebsd/usr.sbin/bhyve