fix metal build

Author: stuartcarnie

src/backend/metal/build.rs

@@ -55,7 +55,7 @@ fn main() {
         out_path.set_extension("air");
 
         let status = Command::new("xcrun")
-            .args(&["-sdk", sdk_name, "metal"])
+            .args(&["-sdk", sdk_name, "metal", "-c"])
             .arg(shader_path.as_os_str())
             .arg("-o")
             .arg(out_path.as_os_str())

src/backend/metal/shaders/blit.metal

@@ -1,4 +1,4 @@
-#include "macros.metal"
+#include "macros.h"
 #include <metal_stdlib>
 using namespace metal;
 

src/backend/metal/shaders/clear.metal

@@ -1,4 +1,4 @@
-#include "macros.metal"
+#include "macros.h"
 #include <metal_stdlib>
 using namespace metal;