[libc++] NFC: Normalize `#endif //` comment indentation

GitOrigin-RevId: 4cd6ca102a94e1b64ba3f940cc26b4d7b2b82964
diff --git a/src/mutex.cpp b/src/mutex.cpp
index efb9a90..36362e3 100644
--- a/src/mutex.cpp
+++ b/src/mutex.cpp
@@ -209,7 +209,7 @@
 #ifndef _LIBCPP_NO_EXCEPTIONS
         try
         {
-#endif  // _LIBCPP_NO_EXCEPTIONS
+#endif // _LIBCPP_NO_EXCEPTIONS
             flag = 1;
             func(arg);
             flag = ~once_flag::_State_type(0);
@@ -220,7 +220,7 @@
             flag = 0;
             throw;
         }
-#endif  // _LIBCPP_NO_EXCEPTIONS
+#endif // _LIBCPP_NO_EXCEPTIONS
     }
 #else // !_LIBCPP_HAS_NO_THREADS
     __libcpp_mutex_lock(&mut);
@@ -231,7 +231,7 @@
 #ifndef _LIBCPP_NO_EXCEPTIONS
         try
         {
-#endif  // _LIBCPP_NO_EXCEPTIONS
+#endif // _LIBCPP_NO_EXCEPTIONS
             __libcpp_relaxed_store(&flag, once_flag::_State_type(1));
             __libcpp_mutex_unlock(&mut);
             func(arg);
@@ -250,7 +250,7 @@
             __libcpp_condvar_broadcast(&cv);
             throw;
         }
-#endif  // _LIBCPP_NO_EXCEPTIONS
+#endif // _LIBCPP_NO_EXCEPTIONS
     }
     else
         __libcpp_mutex_unlock(&mut);