buffer: harden validation of buffer allocation size

This makes using `NaN` as the buffer size throw an error.

Fixes: https://github.com/nodejs/node/issues/26151

PR-URL: https://github.com/nodejs/node/pull/26162


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>