Merge #2267

2267: [mtl] new autorelease r=grovesNL a=kvark

Fixes the time wasted on setting up temporary autorelease pools, mostly. Although the resulting FPS doesn't appear to be affected. At least we no longer depend on core-foundation :)
cc @jrmuizel (and thanks!) for the way it looks now

PR checklist:
- [ ] `make` succeeds (on *nix)
- [ ] `make reftests` succeeds
- [x] tested examples with the following backends: metal
- [ ] `rustfmt` run on changed code


Co-authored-by: Dzmitry Malyshau <kvarkus@gmail.com>

src/backend/metal/Cargo.toml

@@ -25,10 +25,9 @@ log = { version = "0.4", features = ["release_max_level_error"] }
 winit = { version = "0.16", optional = true }
 metal-rs = "0.10.1"
 foreign-types = "0.3"
-objc = "0.2"
+objc = "0.2.5"
 block = "0.1"
 cocoa = "0.15"
-core-foundation = "0.6"
 core-graphics = "0.14"
 dispatch = "0.1"
 smallvec = "0.6"