Debug Info: Prepare DebugLocEntry to handle more than a single value per
entry. This is in preparation for generic DW_OP_piece support.
No functional change so far.

http://reviews.llvm.org/D3373
rdar://problem/15928306
Debug info: Refactor EmitDwarfRegOpPiece to be a member function of
AsmPrinter.
No functional change.

http://reviews.llvm.org/D3373
rdar://problem/15928306