Auto merge of #343 - zubivan:master, r=jdm

Add CGConfigureDisplayOrigin

Adds a wrapper for [CGConfigureDisplayOrigin](https://developer.apple.com/documentation/coregraphics/1454090-cgconfiguredisplayorigin) which has the following signature:

``` c
func CGConfigureDisplayOrigin(_ config: CGDisplayConfigRef?,
                            _ display: CGDirectDisplayID,
                            _ x: Int32,
                            _ y: Int32) -> CGError
```

Please let me know if there is anything I can improve here.

I'm currently working on the small utility heavily relying on CoreGraphics API, so expect more of those to come as I go. :)

core-graphics/src/display.rs

@@ -200,6 +200,22 @@ impl CGDisplay {
         }
     }
 
+    // Configures the origin of a display in the global display coordinate space.
+    pub fn configure_display_origin(
+        &self,
+        config_ref: &CGDisplayConfigRef,
+        x: i32,
+        y: i32,
+    ) -> Result<(), CGError> {
+        let result = unsafe { CGConfigureDisplayOrigin(*config_ref, self.id, x, y) };
+
+        if result == 0 {
+            Ok(())
+        } else {
+            Err(result)
+        }
+    }
+
     /// Returns an image containing the contents of the specified display.
     #[inline]
     pub fn image(&self) -> Option<CGImage> {
@@ -630,6 +646,12 @@ extern "C" {
         mode: ::sys::CGDisplayModeRef,
         options: CFDictionaryRef,
     ) -> CGError;
+    pub fn CGConfigureDisplayOrigin(
+        config: CGDisplayConfigRef,
+        display: CGDirectDisplayID,
+        x: i32,
+        y: i32,
+    ) -> CGError;
 
     pub fn CGDisplayCopyDisplayMode(display: CGDirectDisplayID) -> ::sys::CGDisplayModeRef;
     pub fn CGDisplayModeGetHeight(mode: ::sys::CGDisplayModeRef) -> libc::size_t;