bug#50243: [core-updates-frozen] "multiple definition of..." build failures

[Sarah Morgensen <iskarian@mgsn.dev>]

Hello Guix,

GCC 10 changed the default behavior when encountering multiple
definitions of a global (often an enum) [0].  This causes error messages
like [1]:

--8<---------------cut here---------------start------------->8---
  ld: a.o:(.bss+0x0): multiple definition of `a'; main.o:(.data+0x0): first defined here
--8<---------------cut here---------------end--------------->8---

Gentoo's tracker for this issue [2] also has some more info.  I manually
searched Cuirass build logs and found 28 packages failing on x86_64 with
this error:

arcan-sdl@0.5.5.2-1.b4dd1fb
aris@2.2
blastem@0.6.2
chocolate-doom@3.0.1
crispy-doom@5.8.0
geeqie@1.5
glabels@3.4.1
gmtp@1.3.11
gpredict@2.2.1
gtksheet@4.3.5
jumpnbump@1.61
lablgtk@2.18.10
libappindicator@12.10.0
libopenshot@0.2.5
libsrtp@2.3.0
linsmith@0.99.31
megaglest@3.13.0
mupen64plus-core@2.5
ocaml4.07-lablgtk@1.18.10
ocl-icd@2.2.12
opencpn@5.0.0
pcsxr@1.9.95
pipewire@0.2.7
transcode@1.1.7
transmission-remote-gtk@1.4.1
uget@2.2.1
uim-gtk@1.8.8
uim-qt@1.8.8

I submitted an issue upstream for transmission-remote-gtk [3], but I
haven't taken a look at the others.  Any takers?

[0] https://gcc.gnu.org/gcc-10/porting_to.html
[1] https://wiki.gentoo.org/wiki/Project:Toolchain/Gcc_10_porting_notes/fno_common
[2] https://bugs.gentoo.org/705764
[3] https://github.com/transmission-remote-gtk/transmission-remote-gtk/issues/122

--
Sarah