egl: Add stream-related error descriptions

This change adds descriptions for the following errors to
get_egl_error_str():

  - EGL_BAD_STREAM_KHR
  - EGL_BAD_STATE_KHR
  - EGL_BAD_DEVICE_EXT
  - EGL_BAD_OUTPUT_LAYER_EXT

https://bugzilla.gnome.org/show_bug.cgi?id=779112