build(zig-0.16): update example build instrcutions to work on all platforms

examples/build_options.zig

@@ -0,0 +1,6 @@
+// Stub build_options for standalone example builds (zig build-exe).
+// When using `zig build` from the repo root, the real build_options module is
+// generated by the build system.  This file is only needed when invoking
+// zig build-exe directly from the examples/ directory.
+pub const macos_fsevents = false;
+pub const install_tests = false;