Fallback to 'surfaceless' with auto platforms if no display
Reasons:
- Surfaceless is the safest default if no display. Since it is first, the fallback will always be it (unless a manual list is passed.)
- HAVE_SURFACELESS_PLATFORM seems to guard no os-specific code so should be safe on haiku too.
This is the more conservative version. The more radical thing to do is
always build surfaceless, so the order of platforms never matters at
all and _EGL_NATIVE_PLATFORM
making the fallback always surfaceless.
Edited by John Ericson