[MCJIT] Rewrite RuntimeDyldMachO and its derived classes to use the 'Offset'
field of RelocationValueRef, rather than the 'Addend' field.

This is consistent with RuntimeDyldELF's use of RelocationValueRef, and more
consistent with the semantics of the data being stored (the offset from the
start of a section or symbol).



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217328 91177308-0d34-0410-b5e6-96231b3b80d8
[MCJIT] Revert partial RuntimeDyldELF cleanup that was prematurely committed in
r217328.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217329 91177308-0d34-0410-b5e6-96231b3b80d8
BumpPtrAllocator: do the size check without moving any pointers

Instead of aligning and moving the CurPtr forward, and then comparing
with End, simply calculate how much space is needed, and compare that
to how much is available.

Hopefully this avoids any doubts about comparing addresses possibly
derived from past the end of the slab array, overflowing, etc.

Also add a test where aligning CurPtr would move it past End.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217330 91177308-0d34-0410-b5e6-96231b3b80d8