Revert "[MC] Factor MCObjectStreamer::addFragmentAtoms out of MachO streamer."

This reverts rL331412.  We didn't up using fragment atoms
in the wasm object writer after all.

Differential Revision: https://reviews.llvm.org/D48173

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334734 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed