[MCJIT][SystemZ] Use a simpler expression for indirect relocation offsets.
[MCJIT][SystemZ] Use a simpler expression for indirect relocation offsets.

The expressions 'Reloc.Addend - Addend' and 'Reloc.Offset' should always be
equal in this context. The latter is prefered - we want to remove the
RelocationValueRef::Addend field in the future.





git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@216418 91177308-0d34-0410-b5e6-96231b3b80d8

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