Cross-compiling with clang 3.5 doesn’t work. Here is tht output at link time for CrashReportClient-Linux-Development ; UE4Game will do the same.
1> [24/24] Link CrashReportClient-Linux-Development
1> D:/Unreal/UnrealEngine-release/UnrealEngine-release/Engine/Source/ThirdParty/SDL2/SDL-gui-backend/lib/Linux/arm-unknown-linux-gnueabihf/libSDL2.a(SDL_rpivideo.c.o): In function `RPI_CreateWindow':
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpivideo.c:256: undefined reference to `vc_dispmanx_update_start'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpivideo.c:257: undefined reference to `vc_dispmanx_element_add'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpivideo.c:260: undefined reference to `vc_dispmanx_update_submit_sync'
1> D:/Unreal/UnrealEngine-release/UnrealEngine-release/Engine/Source/ThirdParty/SDL2/SDL-gui-backend/lib/Linux/arm-unknown-linux-gnueabihf/libSDL2.a(SDL_rpivideo.c.o): In function `RPI_VideoInit':
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpivideo.c:151: undefined reference to `bcm_host_init'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpivideo.c:155: undefined reference to `graphics_get_display_size'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpivideo.c:178: undefined reference to `vc_dispmanx_display_open'
1> D:/Unreal/UnrealEngine-release/UnrealEngine-release/Engine/Source/ThirdParty/SDL2/SDL-gui-backend/lib/Linux/arm-unknown-linux-gnueabihf/libSDL2.a(SDL_rpimouse.c.o): In function `RPI_WarpMouseGlobal':
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:231: undefined reference to `vc_dispmanx_update_start'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:233: undefined reference to `vc_dispmanx_rect_set'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:234: undefined reference to `vc_dispmanx_element_change_attributes'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:246: undefined reference to `vc_dispmanx_update_submit'
1> D:/Unreal/UnrealEngine-release/UnrealEngine-release/Engine/Source/ThirdParty/SDL2/SDL-gui-backend/lib/Linux/arm-unknown-linux-gnueabihf/libSDL2.a(SDL_rpimouse.c.o): In function `RPI_FreeCursor':
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:192: undefined reference to `vc_dispmanx_update_start'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:194: undefined reference to `vc_dispmanx_element_remove'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:196: undefined reference to `vc_dispmanx_update_submit_sync'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:201: undefined reference to `vc_dispmanx_resource_delete'
1> D:/Unreal/UnrealEngine-release/UnrealEngine-release/Engine/Source/ThirdParty/SDL2/SDL-gui-backend/lib/Linux/arm-unknown-linux-gnueabihf/libSDL2.a(SDL_rpimouse.c.o): In function `RPI_ShowCursor':
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:155: undefined reference to `vc_dispmanx_rect_set'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:156: undefined reference to `vc_dispmanx_rect_set'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:158: undefined reference to `vc_dispmanx_update_start'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:161: undefined reference to `vc_dispmanx_element_add'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:172: undefined reference to `vc_dispmanx_update_submit_sync'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:123: undefined reference to `vc_dispmanx_update_start'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:125: undefined reference to `vc_dispmanx_element_remove'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:127: undefined reference to `vc_dispmanx_update_submit_sync'
1> D:/Unreal/UnrealEngine-release/UnrealEngine-release/Engine/Source/ThirdParty/SDL2/SDL-gui-backend/lib/Linux/arm-unknown-linux-gnueabihf/libSDL2.a(SDL_rpimouse.c.o): In function `RPI_CreateCursor':
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:81: undefined reference to `vc_dispmanx_resource_create'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:83: undefined reference to `vc_dispmanx_rect_set'
1> /home/rcl/build/2015-05-01/SDL-gui-backend/src/video/raspberry/SDL_rpimouse.c:90: undefined reference to `vc_dispmanx_resource_write_data'
I have no idea where this RPi stuff comes from, Iam not targetting Raspberry at all.