Heal HEID

- eqForeignObjZh in include/PrimOps.h didn't have quite the right
  shape (the result is a macro arg). hslibs/lang/ForeignObj
  wasn't up on the change to eqForeignObj now being a primop.

- recent ghc/compiler/deSugar/ changes broke the handling of
  CCall & FFI decls quite a bit. Backed out most the rewrites
  of Type.splitFoo to TcType.tcSplitFoo (i.e., now back to using
  TcType.tcSplitFoo).

  The backed-out newtype-related changes were by no means accidental.
  But, I don't profess to understand their intention to make the
  proper fix, so my change is just a stop-gap measure to get HEAD
  back to the land of the living.

- recent changes to the behaviour of 'hiding' & qualified names
  broke hslibs/lang/CString hslibs/data/edison/Seq/ListSeq,
  hslibs/data/edison/Coll/TestOrdBag, hslibs/data/edison/Coll/UnbalancedSet,
  hslibs/data/edison/Coll/TestOrdSet, hslibs/data/edison/Seq/TestSeq

- rename 64-bit 'primop' funs that now live in lib/std/cbits/longlong.c
  back to what they used to be called (i.e., prefixed with "stg_").
  Why?
     - less likely they'll clash with other (user supplied) entry points
       at link-time.
     - matches protos in ghc/includes/PrimOp.h