add enough support for indirect branch for the feature test to pass
(assembler,asmprinter, bc reader+writer) and document it.  Codegen
currently aborts on it.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85274 91177308-0d34-0410-b5e6-96231b3b80d8
17 files changed