[libc++][NFC] Update namespace comments in include/

update the namspace comments in include/

Reviewed By: ldionne, #libc

Spies: smeenai, libcxx-commits

Differential Revision: https://reviews.llvm.org/D114947

NOKEYCHECK=True
GitOrigin-RevId: d2b0df35afb7184f5a68f67d6ed0c6230688df7f
diff --git a/include/tuple b/include/tuple
index 2e3d196..8ee5c2e 100644
--- a/include/tuple
+++ b/include/tuple
@@ -1200,7 +1200,7 @@
     static_assert(!is_same<_T1, _T1>::value, "type not in empty type list");
 };
 
-} // namespace __find_detail;
+} // namespace __find_detail
 
 template <typename _T1, typename... _Args>
 struct __find_exactly_one_t
@@ -1257,7 +1257,7 @@
 
 namespace {
   constexpr __ignore_t<unsigned char> ignore = __ignore_t<unsigned char>();
-}
+} // namespace
 
 template <class... _Tp>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11