[PATCH] Upstream: fix warning when building with BoringSSL

[Piotr Sikora]

Hey Maxim,

> I have no strong objections, but the patch as you've submitted
> casts to "const char *", while just "char *" should be enough.

While cast to "char *" also works, I must admit that I'm confused as
to why do you prefer to cast to a type that "should be enough" instead
of a type that's expected by the function.

Anyway, either one is an improvement over current situation, so please commit.

Best regards,
Piotr Sikora