lavapipe: add support for non-dri loader on linux
If you build --glx=gallium-xlib then lavapipe will fail to link this should let it use the non-dri paths on Linux in that case
@brianp this should build in the use case you mentioned -Dplatforms=x11 -Dvulkan-drivers=swrast -Dglx=gallium-xlib -Dgallium-drivers=swrast -Ddri-drivers=
Edited by Dave Airlie