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

GitOrigin-RevId: 4cd6ca102a94e1b64ba3f940cc26b4d7b2b82964
diff --git a/include/cmath b/include/cmath
index 1efd4e4..5f41366 100644
--- a/include/cmath
+++ b/include/cmath
@@ -672,4 +672,4 @@
 
 _LIBCPP_POP_MACROS
 
-#endif  // _LIBCPP_CMATH
+#endif // _LIBCPP_CMATH