Got the EmulateInstruction CFI code a lot closer to producing CFI data.

Switch the EmulateInstruction to use the standard RegisterInfo structure
that is defined in the lldb private types intead of passing the reg kind and
reg num everywhere. EmulateInstruction subclasses also need to provide
RegisterInfo structs given a reg kind and reg num. This eliminates the need
for the GetRegisterName() virtual function and allows more complete information
to be passed around in the read/write register callbacks. Subclasses should
always provide RegiterInfo structs with the generic register info filled in as
well as at least one kind of register number in the RegisterInfo.kinds[] array.

llvm-svn: 130256