Revert "[DebugInfo] Insert DW_OP_deref when spilling indirect DBG_VALUEs"

This reverts r313640, originally r313400, one more time for essentially
the same issue. My BitVector of spilled location numbers isn't working
because we coalesce identical DBG_VALUE locations as we rewrite them,
invalidating the location numbers used to index the BitVector.

llvm-svn: 313679