Since we are having issues with the new LLVM MC disassembler, we can have

them both installed with the LLVM MC version being the default. I renamed the
name of the LLVM MC disassembler plug-in to "llvm-mc" and the LLVM enhanced
disassembly plug-in to "llvm-edis" and they can both be installed for now.

To use the "llvm-edis" disassembler, you can just specify it while disassembling:

(lldb) disassemble --plugin llvm-edis --name main
(lldb) disassemble --plugin llvm-mc --name main

This will allow us to compare the output of the two disassembler and eventually
deprecate the old one when the new one is ready. But it does use the new disassembler
by default so we continue to test it on a daily basis.

llvm-svn: 153231