Rename weston_compositor EGLDisplay member to egl_display

EGLDisplay is helpfully typedeffed as void *, which means that you won't
get conflicting-pointer-type warnings if you accidentally confuse it
with weston_compositor::wl_display.  Rename it to make it more clear
which display you're dealing with, and also rename compositor-wayland's
parent.display member to parent.wl_display.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>
diff --git a/src/compositor.h b/src/compositor.h
index df100d5..b57fc2e 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -273,9 +273,9 @@
 	struct wl_shm *shm;
 	struct wl_signal destroy_signal;
 
-	EGLDisplay display;
-	EGLContext context;
-	EGLConfig config;
+	EGLDisplay egl_display;
+	EGLContext egl_context;
+	EGLConfig egl_config;
 	GLuint fbo;
 	struct weston_shader texture_shader;
 	struct weston_shader solid_shader;