build failure w/ up-to-date checkout

[bch <brad.harder%gmail.com@localhost>]

[...]
dependall ===> external/bsd/file/lib
dependall ===> external/bsd/file/bin
#      link  bin/file
/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/x86_64--netbsd-gcc
--sysroot=/usr/src/obj/destdir.amd64  -pie  -shared-libgcc
-Wl,-z,relro -Wl,--warn-shared-textrel     -o file  file.o
-Wl,-rpath-link,/usr/src/obj/destdir.amd64/lib  -L=/lib -lmagic -lz
/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/nbctfmerge -t -g -L
VERSION -o file file.o
#    create  bin/magic.mgc
/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/nbfile -C -m
/usr/src/external/bsd/file/dist/magic/magdir
#    format  bin/file.html1
if test "" != "yes"; then
/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/nbmandoc -Thtml
-Oman=../html%S/%N.html -Ostyle=../style.css
/usr/src/external/bsd/file/dist/doc/file.1 > file.html1.tmp &&  mv
file.html1.tmp file.html1;  else
PATH=/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/lib/groff:${PATH}
/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/nbgroff -Tlatin1
-mdoc2html /usr/src/external/bsd/file/dist/doc/file.1   >
file.html1.tmp && mv file.html1.tmp file.html1;  fi
dependall ===> external/bsd/flex
dependall ===> external/bsd/flex/lib
dependall ===> external/bsd/flex/bin
nbmake[7]: /usr/src/external/bsd/flex/bin/obj/.depend, 1072: ignoring
stale .depend for /usr/src/external/bsd/flex/dist/src/skel.c
#    create  bin/skel.d
CC=/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/x86_64--netbsd-gcc
/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/nbmkdep -f skel.d.tmp
--   -std=gnu99   --sysroot=/usr/src/obj/destdir.amd64 -DHAVE_CONFIG_H
-I/usr/src/external/bsd/flex/bin/../include
-I/usr/src/external/bsd/flex/dist/src
-DLOCALEDIR=\"/usr/share/locale\" -I. -I/usr/src/external/bsd/flex/bin
-DVERSION=\"2.6.3\"     /usr/src/external/bsd/flex/dist/src/skel.c &&
mv skel.d.tmp skel.d
x86_64--netbsd-gcc: error: /usr/src/external/bsd/flex/dist/src/skel.c:
No such file or directory
x86_64--netbsd-gcc: fatal error: no input files
compilation terminated.
nbmkdep: compile failed.

*** Failed target:  skel.d
*** Failed command:
CC=/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/x86_64--netbsd-gcc
/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/nbmkdep -f skel.d.tmp --
-std=gnu99 --sysroot=/usr/src/obj/destdir.amd64 -DHAVE_CONFIG_H
-I/usr/src/external/bsd/flex/bin/../include
-I/usr/src/external/bsd/flex/dist/src
-DLOCALEDIR=\"/usr/share/locale\" -I. -I/usr/src/external/bsd/flex/bin
-DVERSION=\"2.6.3\" /usr/src/external/bsd/flex/dist/src/skel.c && mv
skel.d.tmp skel.d
*** Error code 1

Stop.
nbmake[7]: stopped in /usr/src/external/bsd/flex/bin

*** Failed target:  dependall-bin
*** Failed command: _makedirtarget() { dir="$1"; shift; target="$1";
shift; case "${dir}" in /*) this="${dir}/"; real="${dir}" ;; .)
this="external/bsd/flex/"; real="/usr/src/external/bsd/flex" ;; *)
this="external/bsd/flex/${dir}/";
real="/usr/src/external/bsd/flex/${dir}" ;; esac; show=${this:-.};
echo "${target} ===> ${show%/}${1:+ (with: $@)}"; cd "${real}" &&
/usr/src/obj/tooldir.NetBSD-7.99.53-amd64/bin/nbmake
_THISDIR_="${this}" "$@" ${target}; }; _makedirtarget bin dependall
*** Error code 1

[...]