All addressing modes are now exposed. The only remaining relocated forms

All addressing modes are now exposed.  The only remaining relocated forms
are for function prologue.

TODO: move external symbols over to using RelLit.
    : have a pattern that matches constpool|globaladdr
    : have a pattern that matches (add x imm) -> x, imm or (...) -> ..., 0

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25003 91177308-0d34-0410-b5e6-96231b3b80d8