> This was detected while running the tests with the `-Wconditional-uninitialized` flag
>
> ```
> ./autogen.sh
> CC=clang CFLAGS="-Wconditional-uninitialized" ./configure
> make check
> ```
>
> The resulting warning is a false positive, but setting the value to -1
> ensures that the CHECK below will fail if recid is never written to.
This is a backport of secp256k1#899
It should allow us to finally land D9110