FreeBSD_HEAD_arm64 - Build #3474 - Fixed

[jenkins-admin at FreeBSD.org]

FreeBSD_HEAD_arm64 - Build #3474 - Fixed:

Build information: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_arm64/3474/
Full change log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_arm64/3474/changes
Full build log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_arm64/3474/console

Change summaries:

302222 by delphij:
Fix build: explicitly reference the generated magic.h as dependency
of mkmagic and point its location.

Reported by:	jenkins
Pointy hat to:	delphij
MFC after:	2 weeks
X-MFC-With:	302221
Approved by:	re (kib)