Use TableGen to emit information for dwarf register numbers.

Use TableGen to emit information for dwarf register numbers.
This makes DwarfRegNum to accept list of numbers instead.
Added three different "flavours", but only slightly tested on x86-32/linux.
Please check another subtargets if possible,

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43997 91177308-0d34-0410-b5e6-96231b3b80d8