Reverse ordering of base and derived pointer during safepoint lowering.

Reverse ordering of base and derived pointer during safepoint lowering.

According to the documentation in StackMap section for the safepoint we should have:
"The first Location in each pair describes the base pointer for the object. The second is the derived pointer actually being relocated."
But before this change we emitted them in reverse order - derived pointer first, base pointer second.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237126 91177308-0d34-0410-b5e6-96231b3b80d8