Process::GetRandomNumber(): fix insecure RNG

This could have generated non-random output under error conditions in release
builds.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210065 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch64] Correctly deal with VPR stack parameter passing.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210067 91177308-0d34-0410-b5e6-96231b3b80d8