window: improve EGL-related error messages
window: improve EGL-related error messages

Make them explicitly mention EGL, otherwise one can easily think that
"failed to initialize display" refers to Wayland display.

Also explicitly mention falling back to wl_shm. I tested this with a
LD_PRELOAD trick that overrides eglBindAPI and makes it fail.

Signed-off-by: Pekka Paalanen <6c0263d81461c956d504307112a4ce25eaacc3d1@gmail.com>

xorgy/weston,kwm81/weston,giucam/weston,mchalupa/weston,krezovic/weston,udoprog/weston,sir-murray/weston,kwm81/weston,jonnylamb/weston,eyolfson/weston,mchalupa/weston,Gnurou/weston,Fantu/compositor-spice,udoprog/weston,sir-murray/weston,Gnurou/weston,Fantu/compositor-spice,Fantu/compositor-spice,xorgy/weston,eyolfson/weston,krezovic/weston,jonnylamb/weston,Tarnyko/weston-xdg_surface_present,Tarnyko/weston-xdg_surface_present,giucam/weston