Initial support for the cfi directives. This is just enough to get

f:
        .cfi_startproc
        nop
        .cfi_endproc

assembled (on ELF).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121434 91177308-0d34-0410-b5e6-96231b3b80d8
32 files changed