CodeView: Provide a .def file with the register ids
The list of register ids was previously written out in a couple of dirrent
places. This puts it in a .def file and also adds a few more registers (e.g.
the x87 regs) which should lead to more readable dumps, but I didn't include
the whole list since that seems unnecessary.
X86_MC::initLLVMToSEHAndCVRegMapping is pretty ugly, but at least it's not
relying on magic constants anymore. The TODO of using tablegen still stands.
Differential revision: https://reviews.llvm.org/D38480
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314821
91177308-0d34-0410-b5e6-
96231b3b80d8