DRM-4.7 branch: buildkernel failed

Hello,

I tried building the 'drm-next-4.7' branch of the FreeBSDDesktop fork of
12.0-CURRENT, but clang fails to find required headers:

[log truncated to failing source file]
--- ati_pcigart.o ---
/usr/local/bin/clang38 -target x86_64-unknown-freebsd12.0
--sysroot=/usr/obj/usr/src/current/freebsd-base-graphics/tmp
-B/usr/obj/usr/src/current/freebsd-base-graphics/tmp/usr/bin -c -O2 -pipe
-fno-strict-aliasing -march=native -g -nostdinc  -I.
-I/usr/src/current/freebsd-base-graphics/sys
-I/usr/src/current/freebsd-base-graphics/sys/contrib/libfdt -D_KERNEL
-DHAVE_KERNEL_OPTION_HEADERS -include opt_global.h  -fno-omit-frame-pointer
-mno-omit-leaf-frame-pointer -MD  -MF.depend.ati_pcigart.o -MTati_pcigart.o
-mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float
-fno-asynchronous-unwind-tables -ffreestanding -fwrapv -fstack-protector
-gdwarf-2 -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes
-Wmissing-prototypes -Wpointer-arith -Winline -Wcast-qual -Wundef
-Wno-pointer-sign -D__printf__=__freebsd_kprintf__ -Wmissing-include-dirs
-fdiagnostics-show-option -Wno-unknown-pragmas
-Wno-error-tautological-compare -Wno-error-empty-body
-Wno-error-parentheses-equality -Wno-error-unused-function
-Wno-error-pointer-sign -Wno-error-shift-negative-value  -mno-aes -mno-avx
-std=iso9899:1999 -Werror
/usr/src/current/freebsd-base-graphics/sys/dev/drm/ati_pcigart.c
/usr/src/current/freebsd-base-graphics/sys/dev/drm/ati_pcigart.c:34:10:
fatal error: 'linux/export.h' file not found
#include <linux/export.h>
         ^
1 error generated.
*** [ati_pcigart.o] Error code 1

make[2]: stopped in /usr/obj/usr/src/current/freebsd-base-graphics/sys/LOCAL
--- modules-all ---
--- fm.o ---
ctfconvert -L VERSION -g fm.o
--- inffast.o ---
ctfconvert -L VERSION -g inffast.o
--- deflate.o ---
ctfconvert -L VERSION -g deflate.o
A failure has been detected in another branch of the parallel make

make[4]: stopped in /usr/src/current/freebsd-base-graphics/sys/modules/zfs
*** [all_subdir_zfs] Error code 2

make[3]: stopped in /usr/src/current/freebsd-base-graphics/sys/modules
1 error

make[3]: stopped in /usr/src/current/freebsd-base-graphics/sys/modules
*** [modules-all] Error code 2

make[2]: stopped in /usr/obj/usr/src/current/freebsd-base-graphics/sys/LOCAL
2 errors

make[2]: stopped in /usr/obj/usr/src/current/freebsd-base-graphics/sys/LOCAL
*** [buildkernel] Error code 2

make[1]: stopped in /usr/src/current/freebsd-base-graphics
1 error

make[1]: stopped in /usr/src/current/freebsd-base-graphics
*** [buildkernel] Error code 2

make: stopped in /usr/src/current/freebsd-base-graphics
1 error

make: stopped in /usr/src/current/freebsd-base-graphics
[EOF]

where LOCAL is my KERNCONF.

I had attempted a previous build of this branch, and it failed in exactly
the same way. Should I see with the maintainers of the branch?

uname -a:
FreeBSD setun-90 11.0-STABLE FreeBSD 11.0-STABLE #0 r308484: Thu Nov 10
23:22:53 CET 2016     root_at_setun-90:/usr/obj/usr/src/stable/sys/LOCAL  amd64

dmesg | grep CPU:
CPU: Intel(R) Core(TM) i7-6500U CPU _at_ 2.50GHz (2592.09-MHz K8-class CPU)

Cheers,