Make weston_output_transform_coordinate more sane

The output is renamed "output" from "x11_output" and the input coordinates
are changed to wl_fixed_t from int.  This way it is useable in
compositor-wayland as well as compositor-x11 and evdev.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
diff --git a/src/compositor.h b/src/compositor.h
index 2487577..eb105a5 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -1156,8 +1156,8 @@
 void
 weston_output_destroy(struct weston_output *output);
 void
-weston_output_transform_coordinate(struct weston_output *x11_output,
-				   int device_x, int device_y,
+weston_output_transform_coordinate(struct weston_output *output,
+				   wl_fixed_t device_x, wl_fixed_t device_y,
 				   wl_fixed_t *x, wl_fixed_t *y);
 
 void