[RuntimeDyld] Add support for MachO __jump_table and __pointers sections, and
SECTDIFF relocations on 32-bit x86.

This fixes several of the MCJIT regression test failures that show up on 32-bit
builds.

<rdar://problem/16886294>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208635 91177308-0d34-0410-b5e6-96231b3b80d8