Make EGL/GLESv2 dependencies optional

Introduce --disable-egl switch for configure to disable
EGL/GLESv2 support.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
diff --git a/src/compositor-x11.c b/src/compositor-x11.c
index c5c4248..7ae2b75 100644
--- a/src/compositor-x11.c
+++ b/src/compositor-x11.c
@@ -884,7 +884,7 @@
 			return NULL;
 		}
 	} else {
-		if (gl_renderer_output_create(&output->base, output->window) < 0)
+		if (gl_renderer_output_create(&output->base, (EGLNativeWindowType)output->window) < 0)
 			return NULL;
 	}
 
@@ -1474,7 +1474,7 @@
 			goto err_xdisplay;
 	}
 	else {
-		if (gl_renderer_create(&c->base, c->dpy, gl_renderer_opaque_attribs,
+		if (gl_renderer_create(&c->base, (EGLNativeDisplayType)c->dpy, gl_renderer_opaque_attribs,
 				NULL) < 0)
 			goto err_xdisplay;
 	}