Eliminate PPC instruction decoding ambiguities

The instruction definitions in the PPC backend have a number of variants
defined for the same instruction to represent differences between 64-bit and
32-bit semantics. In order to generate a disassembler for the PPC backend, we
need to mark all but one of these as CodeGen only.

No functionality change intended; this is prep work for PPC disassembly
support.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197535 91177308-0d34-0410-b5e6-96231b3b80d8
Fix N32 registers and stack alignment.

This patch fixes the "n" and "S" components of the data layout for mips. Clang
already gets this right.

This will be tested in clang.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197536 91177308-0d34-0410-b5e6-96231b3b80d8
DebugInfo: Introduce new DIValue, DIETypeSignature to encode references to type units via their signatures

This simplifies type unit and type unit reference creation as well as
setting the stage for inter-type hashing across type unit boundaries.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197539 91177308-0d34-0410-b5e6-96231b3b80d8