Add explicit () return types for msg_send!

`msg_send!` with an unconstrained return type used to be deduced to have
the return type `()`. This is no longer the case after the stabilization
of the `!` (never) type (rust-lang/rust#48950),
and it'll be deduced to be `!`.

This commit adds explicit return types to preserve the old behavior.

NGSEngine/src/ngsgfx/src/backend/metal/src/metal-rs/src/lib.rs

@@ -274,13 +274,13 @@ impl CAMetalLayer {
 
     pub fn set_presents_with_transaction(&self, transaction: bool) {
         unsafe {
-            msg_send![self.0, setPresentsWithTransaction:transaction];
+            msg_send![self.0, setPresentsWithTransaction:transaction]
         }
     }
 
     pub fn set_framebuffer_only(&self, framebuffer_only: bool) {
         unsafe {
-            msg_send![self.0, setFramebufferOnly:framebuffer_only];
+            msg_send![self.0, setFramebufferOnly:framebuffer_only]
         }
     }
 
@@ -304,7 +304,7 @@ impl CAMetalLayer {
 
     pub fn remove_all_animations(&self) {
         unsafe {
-            msg_send![self.0, removeAllAnimations];
+            msg_send![self.0, removeAllAnimations]
         }
     }
 

NGSEngine/src/ngsgfx/src/wsi/metal/src/lib.rs

@@ -233,7 +233,7 @@ impl wsi_core::NewWindow for MetalWindow {
 
             let ns_cs_name = NSString::alloc(ptr::null_mut()).init_str(cs_name);
             let colorspace = CGColorSpaceCreateWithName(mem::transmute(ns_cs_name));
-            msg_send![ns_cs_name, release];
+            let () = msg_send![ns_cs_name, release];
 
             layer.set_edge_antialiasing_mask(0);
             layer.set_masks_to_bounds(true);

NGSEngine/src/zangfx/src/backend/metal/src/metal-rs/src/lib.rs

@@ -274,13 +274,13 @@ impl CAMetalLayer {
 
     pub fn set_presents_with_transaction(&self, transaction: bool) {
         unsafe {
-            msg_send![self.0, setPresentsWithTransaction:transaction];
+            msg_send![self.0, setPresentsWithTransaction:transaction]
         }
     }
 
     pub fn set_framebuffer_only(&self, framebuffer_only: bool) {
         unsafe {
-            msg_send![self.0, setFramebufferOnly:framebuffer_only];
+            msg_send![self.0, setFramebufferOnly:framebuffer_only]
         }
     }
 
@@ -304,7 +304,7 @@ impl CAMetalLayer {
 
     pub fn remove_all_animations(&self) {
         unsafe {
-            msg_send![self.0, removeAllAnimations];
+            msg_send![self.0, removeAllAnimations]
         }
     }