pkg/53659: pkgsrc-2018Q3 devel/protobuf build failure on NetBSD/i386 8.0

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

>Number:         53659
>Category:       pkg
>Synopsis:       pkgsrc-2018Q3 devel/protobuf build failure on NetBSD/i386 8.0
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Oct 08 03:15:00 +0000 2018
>Originator:     Izumi Tsutsui
>Release:        NetBSD 8.0
>Organization:
>Environment:
System: NetBSD mirage 8.0 NetBSD 8.0 (GENERIC) #0: Tue Jul 17 14:59:51 UTC 2018 mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/i386/compile/GENERIC i386
Architecture: i386
Machine: i386
>Description:
pkgsrc-2018Q3 pkgsrc/devel/protobuf build fails on NetBSD/i386 8.0:

---
 :

/bin/sh ../libtool  --tag=CXX   --mode=link c++ -pthread  -DHAVE_PTHREAD=1 -DHAVE_ZLIB=1 -Wall -Wno-sign-compare  -O2 -D_FORTIFY_SOURCE=2 -I/usr/pkg/include -I/usr/include -pthread  -L/usr/pkg/lib -L/usr/lib -Wl,-R/usr/lib -Wl,-R/usr/pkg/lib -o protoc google/protobuf/compiler/main.o  libprotobuf.la libprotoc.la -lz 
libtool: link: c++ -pthread -DHAVE_PTHREAD=1 -DHAVE_ZLIB=1 -Wall -Wno-sign-compare -O2 -D_FORTIFY_SOURCE=2 -I/s/obj.i386/pkgsrc/devel/protobuf/work.i386/.buildlink/include -pthread -Wl,-rpath -Wl,/usr/pkg/lib -o .libs/protoc google/protobuf/compiler/main.o  -L/s/obj.i386/pkgsrc/devel/protobuf/work.i386/protobuf-3.6.0/src/.libs -L/s/obj.i386/pkgsrc/devel/protobuf/work.i386/.buildlink/lib -L./.libs -lprotoc -lprotobuf -lz -pthread -Wl,-rpath,/usr/pkg/lib
/s/obj.i386/pkgsrc/devel/protobuf/work.i386/protobuf-3.6.0/src/.libs/libprotobuf.so: undefined reference to `__atomic_fetch_add_8'
gmake[2]: *** [Makefile:3480: protoc] Error 1
gmake[2]: Leaving directory '/s/obj.i386/pkgsrc/devel/protobuf/work.i386/protobuf-3.6.0/src'
gmake[1]: *** [Makefile:1537: all-recursive] Error 1
gmake[1]: Leaving directory '/s/obj.i386/pkgsrc/devel/protobuf/work.i386/protobuf-3.6.0'
gmake: *** [Makefile:1444: all] Error 2
*** Error code 2

---

A full build log is in the following gist:
 https://gist.github.com/tsutsui/8f7e96edec02ef3f3441574890f90497

Note build on NetBSD/amd64 8.0 works.

>How-To-Repeat:
Build pkgsrc/devel/protobuf on NetBSD/i386 8.0

>Fix: