$ STEAM_RUNTIME=0 steam
Running Steam on gentoo 13.0 64-bit
STEAM_RUNTIME is disabled by the user
/home/micko/.local/share/Steam/steam.sh: line 710: LD_LIBRARY_PATH: unbound variable

$ LD_LIBRARY_PATH="" STEAM_RUNTIME=0 steam
Running Steam on gentoo 13.0 64-bit
STEAM_RUNTIME is disabled by the user
Installing breakpad exception handler for appid(steam)/version(1431729692)
Installing breakpad exception handler for appid(steam)/version(1431729692)
Installing breakpad exception handler for appid(steam)/version(1431729692)
Gtk-Message: Failed to load module "canberra-gtk-module"
Installing breakpad exception handler for appid(steam)/version(1431729692)
[0519/214838:ERROR:browser_main_loop.cc(170)] Running without the SUID sandbox! See https://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment for more information on developing with the sandbox on.
Installing breakpad exception handler for appid(steamwebhelper)/version(20150514174016)
Installing breakpad exception handler for appid(steamwebhelper)/version(1431625216)
Installing breakpad exception handler for appid(steamwebhelper)/version(20150514174016)
Installing breakpad exception handler for appid(steamwebhelper)/version(1431729692)
Installing breakpad exception handler for appid(steamwebhelper)/version(1431729692)
/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/vgui2/src/../vgui_surfacelib/FontManager.cpp (276) : Assertion Failed: descs.Count() >= 1
Assert( Assertion Failed: descs.Count() >= 1 ):/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/vgui2/src/../vgui_surfacelib/FontManager.cpp:276

Installing breakpad exception handler for appid(steam)/version(1431729692)
assert_20150519214839_6.dmp[3230]: Uploading dump (out-of-process)
/tmp/dumps/assert_20150519214839_6.dmp
/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/vgui2/src/../vgui_surfacelib/FontManager.cpp (276) : Assertion Failed: descs.Count() >= 1
/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/vgui2/src/../vgui_surfacelib/FontManager.cpp (276) : Assertion Failed: descs.Count() >= 1
/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/vgui2/src/../vgui_surfacelib/FontManager.cpp (276) : Assertion Failed: descs.Count() >= 1
/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/steamUI/../common/steam/client_api.cpp (320) : Assertion Failed: ClientAPI_InitGlobalInstance: InternalAPI_Init_Internal failed, most likely because you are missing a 32-bit dependency of steamclient.so (the Steam client is a 32-bit app).

/home/buildbot/buildslave_steam/steam_rel_client_ubuntu12_linux/build/src/steamUI/SteamStartup.cpp (751) : Assertion Failed: ! "There was a problem with your Steam installation.\n" "Please reinstall steam.\n"
Installing breakpad exception handler for appid(steam)/version(1431729692)
[2015-05-19 21:48:37] Startup - updater built May 14 2015 17:40:14
Looks like steam didn't shutdown cleanly, scheduling immediate update check
[2015-05-19 21:48:37] Checking for update on startup
[2015-05-19 21:48:37] Checking for available updates...
[2015-05-19 21:48:38] Download skipped: /client/steam_client_ubuntu12 version 1431729692, installed version 1431729692
[2015-05-19 21:48:38] Nothing to do
[2015-05-19 21:48:38] Verifying installation...
[2015-05-19 21:48:38] Performing checksum verification of executable files
[2015-05-19 21:48:38] Verification complete
[2015-05-19 21:48:40] Shutdown
assert_20150519214839_6.dmp[3230]: Finished uploading minidump (out-of-process): success = no
assert_20150519214839_6.dmp[3230]: error: HTTP response code said error
assert_20150519214839_6.dmp[3230]: file ''/tmp/dumps/assert_20150519214839_6.dmp'', upload no: ''HTTP response code said error''