pkg/54086: sysutils/u-boot-bananapi doesn't build with WRKOBJDIR

[yamt9999%gmail.com@localhost]

>Number:         54086
>Category:       pkg
>Synopsis:       sysutils/u-boot-bananapi doesn't build with WRKOBJDIR
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Mar 29 07:00:00 +0000 2019
>Originator:     YAMAMOTO Takashi
>Release:        pkgsrc-current on NetBSD-8.0/amd64
>Organization:
>Environment:
NetBSD ushi 8.0 NetBSD 8.0 (GENERIC) #0: Tue Jul 17 14:59:51 UTC 2018  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
when WRKOBJDIR is set, it ends up with the following error.
workaround: unset WRKOBJDIR.


  CC      arch/arm/lib/asm-offsets.s
  CHK     include/generated/asm-offsets.h
  UPD     include/generated/asm-offsets.h
  SHIPPED scripts/dtc/pylibfdt/libfdt.i
  PYMOD   scripts/dtc/pylibfdt/_libfdt.so
/disks/raid1/work/wrkobjdir/sysutils/u-boot-bananapi/work/u-boot-2018.11/scripts/dtc/libfdt/fdt.c:53:17: fatal error: fdt.h: No such file or directory
compilation terminated.
error: command 'cc' failed with exit status 1
scripts/dtc/pylibfdt/Makefile:27: recipe for target 'scripts/dtc/pylibfdt/_libfdt.so' failed
gmake[3]: *** [scripts/dtc/pylibfdt/_libfdt.so] Error 1
scripts/Makefile.build:434: recipe for target 'scripts/dtc/pylibfdt' failed
gmake[2]: *** [scripts/dtc/pylibfdt] Error 2
scripts/Makefile.build:434: recipe for target 'scripts/dtc' failed
gmake[1]: *** [scripts/dtc] Error 2
Makefile:508: recipe for target 'scripts' failed
gmake: *** [scripts] Error 2
*** Error code 2

Stop.
make[1]: stopped in /disks/raid1/work/pkgsrc/pkgsrc/sysutils/u-boot-bananapi
*** Error code 1

Stop.
make: stopped in /home/takashi/store1/work/pkgsrc/pkgsrc/sysutils/u-boot-bananapi
ushi% 
>How-To-Repeat:
write WRKOBJDIR=/somewhere in mk.conf

cd pkgsrc/sysutils/u-boot-bananapi
make
>Fix: