Fix CGDisplayCreateUUIDFromDisplayID linking (again) (#2078)

See also https://github.com/rust-windowing/winit/pull/1626.

The `cocoa` crate links to AppKit, which made the symbol `CGDisplayCreateUUIDFromDisplayID` from ApplicationServices/ColorSync (which AppKit uses internally) available to us on macOS 10.8 to 10.13.

However, this does not work on macOS 10.7 (where AppKit does not link to ColorSync internally). Instead of relying on this, we should just link to ApplicationServices directly.

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
 
+- Fix linking to the `ColorSync` framework on macOS 10.7, and in newer Rust versions.
 - On Web, implement cursor grabbing through the pointer lock API.
 - On X11, add mappings for numpad comma, numpad enter, numlock and pause.
 - On macOS, fix Pinyin IME input by reverting a change that intended to improve IME.

src/platform_impl/macos/ffi.rs

@@ -163,9 +163,18 @@ pub const IO8BitOverlayPixels: &str = "O8";
 pub type CGWindowLevel = i32;
 pub type CGDisplayModeRef = *mut c_void;
 
+// `CGDisplayCreateUUIDFromDisplayID` comes from the `ColorSync` framework.
+// However, that framework was only introduced "publicly" in macOS 10.13.
+//
+// Since we want to support older versions, we can't link to `ColorSync`
+// directly. Fortunately, it has always been available as a subframework of
+// `ApplicationServices`, see:
+// https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/OSX_Technology_Overview/SystemFrameworks/SystemFrameworks.html#//apple_ref/doc/uid/TP40001067-CH210-BBCFFIEG
+//
+// TODO: Remove the WINIT_LINK_COLORSYNC hack, it is probably not needed.
 #[cfg_attr(
     not(use_colorsync_cgdisplaycreateuuidfromdisplayid),
-    link(name = "CoreGraphics", kind = "framework")
+    link(name = "ApplicationServices", kind = "framework")
 )]
 #[cfg_attr(
     use_colorsync_cgdisplaycreateuuidfromdisplayid,