sauerbraten: fix installPhase symlink source

[krishnans2006]

Without this change, package installation fails with the following error:

error: builder for '/nix/store/bqfjr440pyysyrz19qnbvfhjm946l09l-sauerbraten-2020-12-29.drv' failed with exit code 1;
       last 25 log lines:
       >    63 |                     memcpy(curmesh->verts, verts.getbuf(), verts.length()*sizeof(vert)); \
       >       |                           ^
       > engine/obj.h:103:37: note: in expansion of macro 'FLUSHMESH'
       >   103 |                         if(curmesh) FLUSHMESH;
       >       |                                     ^~~~~~~~~
       > engine/obj.h:62:61: note: destination object of size 9223372036854775807 allocated by 'operator new []'
       >    62 |                     curmesh->verts = new vert[verts.length()]; \
       >       |                                                             ^
       > engine/obj.h:103:37: note: in expansion of macro 'FLUSHMESH'
       >   103 |                         if(curmesh) FLUSHMESH;
       >       |                                     ^~~~~~~~~
       > g++ -O3 -fomit-frame-pointer -ffast-math -Wall -fsigned-char -fno-exceptions -fno-rtti -o sauer_client shared/crypto.o shared/geom.o shared/glemu.o shared/stream.o shared/tools.o shared/zip.o engine/3dgui.o engine/bih.o engine/blend.o engine/blob.o engine/client.o engine/command.o engine/console.o engine/cubeloader.o engine/decal.o engine/dynlight.o engine/glare.o engine/grass.o engine/lightmap.o engine/main.o engine/material.o engine/menus.o engine/movie.o engine/normal.o engine/octa.o engine/octaedit.o engine/octarender.o engine/physics.o engine/pvs.o engine/rendergl.o engine/rendermodel.o engine/renderparticles.o engine/rendersky.o engine/rendertext.o engine/renderva.o engine/server.o engine/serverbrowser.o engine/shader.o engine/shadowmap.o engine/sound.o engine/texture.o engine/water.o engine/world.o engine/worldio.o fpsgame/ai.o fpsgame/client.o fpsgame/entities.o fpsgame/fps.o fpsgame/monster.o fpsgame/movable.o fpsgame/render.o fpsgame/scoreboard.o fpsgame/server.o fpsgame/waypoint.o fpsgame/weapon.o -Lenet -lenet -L/usr/X11R6/lib -lX11 `sdl2-config --libs` -lSDL2_image -lSDL2_mixer -lz -lGL -lrt
       > buildPhase completed in 1 minutes 36 seconds
       > Running phase: installPhase
       > Copying '/nix/store/9r2vfk11028yviqiml1679hpiyqavkfq-sauerbraten.desktop/share/applications/sauerbraten.desktop' into '/nix/store/w4zjn50jrj7vmaaygk2rw5bxl7sd43y6-sauerbraten-2020-12-29/share/applications'
       > installPhase completed in 7 minutes 6 seconds
       > Running phase: fixupPhase
       > shrinking RPATHs of ELF executables and libraries in /nix/store/w4zjn50jrj7vmaaygk2rw5bxl7sd43y6-sauerbraten-2020-12-29
       > shrinking /nix/store/w4zjn50jrj7vmaaygk2rw5bxl7sd43y6-sauerbraten-2020-12-29/share/sauerbraten/sauer_client
       > shrinking /nix/store/w4zjn50jrj7vmaaygk2rw5bxl7sd43y6-sauerbraten-2020-12-29/share/sauerbraten/sauer_server
       > checking for references to /build/ in /nix/store/w4zjn50jrj7vmaaygk2rw5bxl7sd43y6-sauerbraten-2020-12-29...
       > patching script interpreter paths in /nix/store/w4zjn50jrj7vmaaygk2rw5bxl7sd43y6-sauerbraten-2020-12-29
       > stripping (with command strip and flags -S -p) in  /nix/store/w4zjn50jrj7vmaaygk2rw5bxl7sd43y6-sauerbraten-2020-12-29/bin
       > ERROR: noBrokenSymlinks: the symlink /nix/store/w4zjn50jrj7vmaaygk2rw5bxl7sd43y6-sauerbraten-2020-12-29/share/icon/sauerbraten.png points to a missing target: /nix/store/w4zjn50jrj7vmaaygk2rw5bxl7sd43y6-sauerbraten-2020-12-29/share/sauerbraten/cube.png
       > ERROR: noBrokenSymlinks: found 1 dangling symlinks, 0 reflexive symlinks and 0 unreadable symlinks
       For full logs, run 'nix log /nix/store/bqfjr440pyysyrz19qnbvfhjm946l09l-sauerbraten-2020-12-29.drv'.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[Jappie3]

nixpkgs-review result

Generated using nixpkgs-review-gha

Command: nixpkgs-review pr 395606

Logs: https://github.com/Jappie3/nixpkgs-review-gha/actions/runs/14236176083

[sivizius]

Any progress? What’s blocking this PR?