two changes:

two changes:
1) nuke ConstDataCoalSection, which is dead.
2) revise my previous patch for rdar://8018335,
  which was completely wrong.  Specifically, it doesn't
  make sense to mark __TEXT,__const_coal as PURE_INSTRUCTIONS,
  because it is for readonly data.  templates (it turns out)
  go to const_coal_nt.  The real fix for rdar://8018335 was
  to give ConstTextCoalSection a section kind of ReadOnly
  instead of Text.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112496 91177308-0d34-0410-b5e6-96231b3b80d8