mitchell's touchups

- benchmark: avoid buffers to avoid a memcpy
- build: keep frame pointers on macOS. There was some debug changes from
  Zig 0.15 and this helps. Also, Apple actually requires/expects x29 to
  always be a frame pointer.
- build/macos: force libSystem symbols instead of compiler-rt
- global: add InitOpts.tool so that ghostty-gen/bench can parse their
  own actions in `+action`
- quirks: provide our own vectorized memset. see the comment for more
  details why.
- synthetic: fix UB by accessing global.io before it was initialized
- terminal/hash_map: force inline for unique repr types. Zig 0.15
  inlined and 0.16 doesn't, measured a huge slowdown in hyperlink
  benchmarks.
- terminal: add explicit `@Vector` usage for storing a run of identical cells
  as well as for scanning printable cells. This auto-vectorized in Zig
  0.15 but not in Zig 0.16. This produces the same assembly.
- unicode: properties and LUT need power-of-two backing integer to avoid
  bad LLVM codegen

src/build/Config.zig

@@ -669,6 +669,17 @@ pub fn fromOptions() Config {
     };
 }
 
+/// Whether release artifacts should omit frame pointers.
+///
+/// Stripped release builds omit them in general, but we always keep frame
+/// pointers on Apple platforms: the Apple arm64 ABI expects x29 to
+/// be a valid frame pointer and Apple's profiling and crash reporting
+/// tools rely on it for backtraces.
+pub fn omitFramePointer(self: *const Config) bool {
+    if (self.target.result.os.tag.isDarwin()) return false;
+    return self.strip;
+}
+
 /// Returns the minimum OS version for the given OS tag. This shouldn't
 /// be used generally, it should only be used for Darwin-based OS currently.
 pub fn osVersionMin(tag: std.Target.Os.Tag) ?std.Target.Query.OsVersion {