> Enable -Wconditional-uninitialized to warn on potentially uninitialized reads.
>
> Fix the sole such warning in Bitcoin Core in GetRdRand(): r1 would be
> set to 0 on rdrand failure, so initializing it to 0 is a non-functional
> change.
>
> From "Intel 64 and IA-32 ArchitecturesSoftware Developer's Manual" [1],
> page 1711: "CF=1 indicates that the data in the destination is valid.
> Otherwise CF=0 and the data in the destination operand will be returned
> as zeros for the specified width."
>
> [1] https://software.intel.com/sites/default/files/managed/39/c5/325462-sdm-vol-1-2abcd-3abcd.pdf
This is a backport of Core PR18843