bug#65491: [PATCH] Improve performance allocating vectors

[Eli Zaretskii]

> Cc: 65491@debbugs.gnu.org, monnier@iro.umontreal.ca
> Date: Sat, 16 Sep 2023 19:12:40 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> The latter one completely broke the 32-bit build --with-wide-int, most
> probably because the last argument to XUNTAG is frequently a pointer
> to a 64-bit type, where uintptr_t is only 32-bit wide.

No, that's not it: the reason is that the _first_ argument is a 64-bit
data type, and then casting XLP(a) to uintptr_t causes the warning,
because uintptr_t is a 32-bit type.