Add exception for libcore/hint.rs to pal lint of tidy script

Author: gnzlbg

src/tools/tidy/src/pal.rs

@@ -42,6 +42,10 @@ const EXCEPTION_PATHS: &[&str] = &[
     "src/libpanic_abort",
     "src/libpanic_unwind",
     "src/libunwind",
+    // black_box implementation is LLVM-version specific and it uses
+    // target_os to tell targets with different LLVM-versions appart
+    // (e.g. `wasm32-unknown-emscripten` vs `wasm32-unknown-unknown`):
+    "src/libcore/hint.rs",
     "src/libstd/sys/", // Platform-specific code for std lives here.
                        // This has the trailing slash so that sys_common is not excepted.
     "src/libstd/os", // Platform-specific public interfaces