Fix zig build and minor improvements (#5702)

- Added zig-pkg directory to gitignore
- Brought min zig version to recent nightly release these improvements
  were completed on
- For linux build, only add rglfw.c if the platform is glfw
- Add a None option to the LinuxDisplayBackend
- Fixed xcode-frameworks dependency and update to using most recent
  commit hash

build.zig.zon

@@ -7,8 +7,8 @@
 
     .dependencies = .{
         .xcode_frameworks = .{
-            .url = "https://pkg.machengine.org/xcode-frameworks/9a45f3ac977fd25dff77e58c6de1870b6808c4a7.tar.gz",
-            .hash = "122098b9174895f9708bc824b0f9e550c401892c40a900006459acf2cbf78acd99bb",
+            .url = "https://pkg.machengine.org/xcode-frameworks/8a1cfb373587ea4c9bb1468b7c986462d8d4e10e.tar.gz",
+            .hash = "N-V-__8AALShqgXkvqYU6f__FrA22SMWmi2TXCJjNTO1m8XJ",
             .lazy = true,
         },
         .emsdk = .{