firefox-41.0 build fails on netbsd-7/i386

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

The recent update of "www/firefox" to v41.0 fails to build on netbsd-7/i386:

NetBSD verthandi.technoskunk.fur 7.0_RC3 NetBSD 7.0_RC3 (VERTHANDI) #88: Thu Sep 10 12:51:56 CDT 2015  sysop%verthandi.technoskunk.fur@localhost:/d0/build/netbsd-7/obj/i386/sys/arch/i386/compile/VERTHANDI i386

[...]
Executing: c++ -o plugin-container -march=i486 -mstackrealign -I/usr/pkg/include -I/usr/include -I/usr/pkg/include/nspr -I/usr/pkg/include/nss/nss -I/usr/X11R7/include -I/usr/X11R7/include/libdrm -I/usr/X11R7/include/freetype2 -Wall -Wempty-body -Woverloaded-virtual -Wsign-compare -Wwrite-strings -Wno-invalid-offsetof -Wcast-align -O2 -I/usr/pkg/include -I/usr/include -I/usr/pkg/include/nspr -I/usr/pkg/include/nss/nss -I/usr/X11R7/include -I/usr/X11R7/include/libdrm -I/usr/X11R7/include/freetype2 -fno-exceptions -fno-strict-aliasing -Dunix -fno-rtti -fno-exceptions -fno-math-errno -std=gnu++0x -pthread -pipe -DNDEBUG -DTRIMMED -O2 -fomit-frame-pointer /d0/build/pkgsrc/www/firefox/work/build/ipc/app/tmpPsRolV.list -lpthread -Wl,-R/usr/pkg/lib/firefox -Wl,-R/usr/pkg/lib -L/usr/pkg/lib -L/usr/lib -Wl,-R/usr/lib -L/usr/pkg/lib/nspr -Wl,-R/usr/pkg/lib/nspr -L/usr/pkg/lib/nss -Wl,-R/usr/pkg/lib/nss -L/usr/X11R7/lib -Wl,-R/usr/X11R7/lib -Wl,-z,noexecstack -Wl,-z,text -Wl,--build-id -rdynamic -Wl,-rpath-link,/d0/build/pkgsrc/www/firefox/work/build/dist/bin -Wl,-rpath-link,/usr/pkg/lib -pie ../../toolkit/library/libxul.so -Wl,-R/usr/pkg/lib/nspr -L/usr/pkg/lib/nspr -lplds4 -lplc4 -lnspr4 -pthread -Wl,--export-dynamic
/d0/build/pkgsrc/www/firefox/work/build/ipc/app/tmpPsRolV.list:
    INPUT("GMPLoader.o")
    INPUT("MozillaRuntimeMain.o")
    INPUT("../../mozglue/build/SSE.o")
    INPUT("../../mozglue/build/dummy.o")
    INPUT("../../memory/mozalloc/Unified_cpp_memory_mozalloc0.o")
    INPUT("../../mozglue/misc/StackWalk.o")
    INPUT("../../mozglue/misc/TimeStamp.o")
    INPUT("../../mozglue/misc/TimeStamp_posix.o")
    INPUT("../../mfbt/Compression.o")
    INPUT("../../mfbt/Decimal.o")
    INPUT("../../mfbt/Unified_cpp_mfbt0.o")
    INPUT("../../memory/fallible/fallible.o")

../../toolkit/library/libxul.so: undefined reference to `__atomic_load_8'
../../toolkit/library/libxul.so: undefined reference to `__atomic_store_8'
../../toolkit/library/libxul.so: undefined reference to `__atomic_fetch_add_8'
/d0/build/pkgsrc/www/firefox/work/mozilla-release/config/rules.mk:666: recipe for target 'plugin-container' failed
gmake[3]: *** [plugin-container] Error 1
[...]

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