pkg/59839: palemoon, firefox, etc., don't build on arm64 any more

>Number:         59839
>Category:       pkg
>Synopsis:       palemoon, firefox, etc., don't build on arm64 any more
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Dec 15 19:40:00 +0000 2025
>Originator:     matthew green
>Release:        11.99.4
>Organization:
>Environment:
NetBSD doctorin-the-tardis.eterna23.net 11.99.4 NetBSD 11.99.4 (_doctorin_) #1: Wed Dec 10 14:13:44 PST 2025  [email protected]:/var/obj/evbarm-aarch64/usr/src3/sys/arch/evbarm/compile/_doctorin_ evbarm

>Description:
trying to build most/all of the mozilla based sources fails now:

exec sh /var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/pale-moon/platform/build/unix/print-failed-commands.sh  /var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/.cwrapper/bin/gcc -std=gnu99 -o avstring.o -c  -DNDEBUG=1 -DTRIMMED=1 -DHAVE_AV_CONFIG_H -I/var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/pale-moon/platform/media/ffvpx/libavutil -I/var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/build/media/ffvpx/libavutil -I/var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/pale-moon/platform/media/ffvpx -I/var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/build/dist/include  -I/var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/build/dist/include/nspr -I/var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/build/dist/include/nss       -fPIC -DPIC  -include /var/obj
 /pkgsrc/www/palemoon/work.doctorin-the-tardis/build/mozilla-config.h -DMOZILLA_CLIENT -MD -MP -MF .deps/avstring.o.pp -DPNG_NO_ASSEMBLER_CODE -I/usr/pkg/include -I/usr/include -I/usr/pkg/include/gli
 b-2.0 -I/usr/pkg/include/gio-unix-2.0 -I/usr/pkg/lib/glib-2.0/include -I/usr/pkg/include/libxml2 -I/usr/pkg/include/ffmpeg7 -I/usr/pkg/include/freetype2 -I/usr/X11R7/include -I/usr/X11R7/include/libdrm -I/usr/pkg/include/harfbuzz -Wall -Wempty-body -Wignored-qualifiers -Wpointer-arith -Wsign-compare -Wtype-limits -Wunreachable-code -Wno-error=maybe-uninitialized -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=multistatement-macros -flifetime-dse=1 -O2 -I/usr/pkg/include -I/usr/include -I/usr/pkg/include/glib-2.0 -I/usr/pkg/include/gio-unix-2.0 -I/usr/pkg/lib/glib-2.0/include -I/usr/pkg/include/libxml2 -I/usr/pkg/include/ffmpeg7 -I/usr/pkg/include/freetype2 -I/usr/X11R7/include -I/usr/X11R7/include/libdrm -I/usr/pkg/include/harfbuzz -fno-strict-aliasing -Dunix -fno-ma
 th-errno -pipe -pthread -g -O2 -fomit-frame-pointer -Wno-parentheses -Wno-pointer-sign -Wno-sign-compare -Wno-switch -Wno-type-limits -Wno-unused-function -Wno-deprecated-declarations -Wno-discarded
 -qualifiers -Wno-maybe-uninitialized -include libavutil_visibility.h  /var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/pale-moon/platform/media/ffvpx/libavutil/avstring.c
In file included from /usr/include/machine/endian.h:4,
                 from /usr/include/sys/types.h:98,
                 from /usr/include/stdlib.h:41,
                 from /var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/pale-moon/platform/media/ffvpx/libavutil/avassert.h:30,
                 from /var/obj/pkgsrc/www/palemoon/work.doctorin-the-tardis/pale-moon/platform/media/ffvpx/libavutil/avstring.c:30:
/usr/include/sys/endian.h: In function 'be16enc':
/usr/include/sys/endian.h:207:1: error: implicit declaration of function 'bswap16' [-Wimplicit-function-declaration]
  207 | __GEN_ENDIAN_ENC(16, be)
      | ^~~~~~~~~~~~~~~~
/usr/include/sys/endian.h: In function 'be32enc':
/usr/include/sys/endian.h:208:1: error: implicit declaration of function 'bswap32' [-Wimplicit-function-declaration]
  208 | __GEN_ENDIAN_ENC(32, be)
      | ^~~~~~~~~~~~~~~~
/usr/include/sys/endian.h: In function 'be64enc':
/usr/include/sys/endian.h:209:1: error: implicit declaration of function 'bswap64' [-Wimplicit-function-declaration]
  209 | __GEN_ENDIAN_ENC(64, be)
      | ^~~~~~~~~~~~~~~~

>How-To-Repeat:
try to build pkgsrc/www/palemoon on arm64 -current
>Fix:
i've worked around the problem by defining __HAVE_SLOW_BSWAP_BUILTIN, but it seems there should be a better solution..