pkg/51383: sys/cdefs.h not found on ubuntu

[prlw1%cam.ac.uk@localhost]

>Number:         51383
>Category:       pkg
>Synopsis:       sys/cdefs.h not found on ubuntu
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Aug 01 11:20:00 +0000 2016
>Originator:     Patrick Welche
>Release:        pkgsrc-current unpriviledged
>Organization:
>Environment:
Ubuntu 16.04.1 LTS
>Description:
Acquired a user login on an ubuntu 16 box, and tried out pkgsrc.
Bootstrapped --unpriviledged.
Tried to build gcc 4.8.4, but sys/cdefs.h not found:

In file included from /usr/include/stdio.h:27:0,
                 from ../../../../gcc-4.8.4/libgcc/../gcc/tsystem.h:87,
                 from ../../../../gcc-4.8.4/libgcc/libgcov.c:27:
/usr/include/features.h:367:25: fatal error: sys/cdefs.h: No such file or directory
 #  include <sys/cdefs.h>
                         ^
compilation terminated.
...
make[4]: Leaving directory '/home/prlw1/pkgsrc/lang/gcc48/work/build/x86_64-debian-linux/libgcc'
...
$ find ~/pkg -name cdefs.h
$ find ~/pkgsrc -name cdefs.h
/home/prlw1/pkgsrc/lang/gcc48/work/gcc-4.8.4/fixincludes/tests/base/sys/cdefs.h
/home/prlw1/pkgsrc/devel/lcc/files/cdefs.h
/home/prlw1/pkgsrc/devel/bmake/files/missing/sys/cdefs.h
/home/prlw1/pkgsrc/pkgtools/libnbcompat/files/nbcompat/cdefs.h
/home/prlw1/pkgsrc/work/bmake/missing/sys/cdefs.h
/home/prlw1/pkgsrc/work/libnbcompat/nbcompat/cdefs.h
/home/prlw1/pkgsrc/work/wrk/devel/bmake/work/bmake/missing/sys/cdefs.h
/home/prlw1/pkgsrc/work/wrk/devel/bmake/work/libnbcompat/nbcompat/cdefs.h
/home/prlw1/pkgsrc/work/wrk/pkgtools/pkg_install/work/libnbcompat/nbcompat/cdefs.h
$

bmake/missing/sys/cdefs.h looks promising...
>How-To-Repeat:

>Fix: