lldb arm64 import.

These changes were written by Greg Clayton, Jim Ingham, Jason Molenda.

It builds cleanly against TOT llvm with xcodebuild.  I updated the
cmake files by visual inspection but did not try a build.  I haven't
built these sources on any non-Mac platforms - I don't think this
patch adds any code that requires darwin, but please let me know if
I missed something.

In debugserver, MachProcess.cpp and MachTask.cpp were renamed to
MachProcess.mm and MachTask.mm as they picked up some new Objective-C
code needed to launch processes when running on iOS.

llvm-svn: 205113
diff --git a/lldb/source/Target/Thread.cpp b/lldb/source/Target/Thread.cpp
index 15768b0..1d7da98 100644
--- a/lldb/source/Target/Thread.cpp
+++ b/lldb/source/Target/Thread.cpp
@@ -2082,6 +2082,7 @@
             case llvm::Triple::x86_64:
             case llvm::Triple::x86:
             case llvm::Triple::arm:
+            case llvm::Triple::arm64:
             case llvm::Triple::thumb:
             case llvm::Triple::mips64:
             case llvm::Triple::hexagon: