[MC] Use the non-EH register mapping in the debug_frame section.

[MC] Use the non-EH register mapping in the debug_frame section.

On 32bits x86 Darwin, the register mappings for the eh_frane and
debug_frame sections are different. Thus the same CFI instructions
should result in different registers in the object file. The
problem isn't target specific though, but it requires that the
mappings for EH register numbers be different from the standard
Dwarf one.

The patch looks a bit clumsy. LLVM uses the EH mapping as
canonical for everything frame related. Thus we need to do a
double conversion EH -> LLVM -> Non-EH, when emitting the
debug_frame section.

Fixes PR22363.

Differential Revision: http://reviews.llvm.org/D7593

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230670 91177308-0d34-0410-b5e6-96231b3b80d8