recomp-ui-snes-pad-defaults test fails to link: missing n64_pad_binds.c

[mstan]

recomp-ui-snes-pad-defaults-test does not link, so the recomp-ui-snes-pad-defaults ctest never runs.

/usr/bin/ld: CMakeFiles/recomp-ui-snes-pad-defaults-test.dir/tests/snes_pad_defaults_test.c.o:
  in function `launcher_binds_save_n64_gamepad':
  undefined reference to `rui_n64_pad_binds_name_is_custom'
  undefined reference to `rui_n64_pad_binds_save_profile'
  undefined reference to `rui_n64_pad_binds_rename'
  undefined reference to `rui_n64_pad_binds_delete'
collect2: error: ld returned 1 exit status

The test TU pulls in src/common/launcher_binds.c, whose launcher_binds_*_n64_gamepad helpers call into rui_n64_pad_binds_*. Those are defined in src/consoles/n64/n64_pad_binds.c, which the target's source list does not include.

Knock-on effect: ninja stops at this failure, so recomp-ui-launcher-nav-backspace-test and recomp-runtime-ui-imgui-test are never built and report Not Run too. Both pass when built explicitly, so those two are collateral, not separate bugs. A full ctest run therefore reports 3 failures out of 20 where there is really only one.

Reproduction (Ubuntu 24.04, gcc, SDL3 3.4.14 from /usr/local):

cmake -G Ninja -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --target recomp-ui-snes-pad-defaults-test

Bisect: reproduces at cb7e54b ("launcher: per-column IDs on shortcut rows, Backspace unbinds, N64 pad profiles"), which is where the rui_n64_pad_binds_* calls entered launcher_binds.c. Not a regression from anything newer.

Found while fixing the Linux AppImage file-picker bug on branch fix/linux-picker-appimage-env; unrelated to that change, and it does not affect consumer builds (FZeroSNESRecomp's Windows and Linux builds are unaffected — only this standalone self-test target).

Low priority: N64 support is deprecated.