Add a definition for UUID_STRING_LEN to uuid.h as needed by a driver.
Also add GUID_INIT for drm-kmod [1].
Submitted by: wulf [1]
Reviewed by: hselasky (earlier), wulf
Differential Revision: https://reviews.freebsd.org/D34235
(cherry picked from commit 97009980c4)
Add a placeholder struct for guid_t which is needed by ACPI consumers
in at least one wireless driver.
Sponsored by: The FreeBSD Foundation
Reviewed by: hselasky
Differential Revision: https://reviews.freebsd.org/D30439
(cherry picked from commit cae1683120)