adds mac only CPU/GPU explicit sync, updates mac env script for latest vulkan version

Author: Matthew Russo

mac-env.sh

@@ -1,5 +1,5 @@
 #!/bin/bash
-export VULKAN_SDK=$HOME/vulkansdk-macos-1.1.92.1/macOS
+export VULKAN_SDK=$HOME/vulkansdk-macos-1.1.97.0/macOS
 export PATH=$VULKAN_SDK/bin:$PATH
 export DYLD_LIBRARY_PATH=$VULKAN_SDK/lib:$DYLD_LIBRARY_PATH
 export VK_ICD_FILENAMES=$VULKAN_SDK/etc/vulkan/icd.d/MoltenVK_icd.json

src/bin/22_descriptor_pools_and_sets.rs

@@ -720,10 +720,10 @@ impl HelloTriangleApplication {
 
         match future {
             Ok(future) => {
-                // This makes sure the CPU stays in sync with the GPU
-                // Not sure if this means we don't need to store the previous_frame_end since we're
-                // explicitly waiting for it?
-                future.wait(None);
+                // This makes sure the CPU stays in sync with the GPU in situations when the CPU is
+                // running "too fast"
+                #[cfg(target_os = "macos")]
+                future.wait(None).unwrap();
 
                 self.previous_frame_end = Some(Box::new(future) as Box<_>);
             }