[Windows] Add a RegisterContextWindows_x64.

With this patch, LLDB can debug x64 executables on Windows with
the same level of functionality as for x86 executables.

llvm-svn: 235935

lldb/source/Plugins/Process/Windows/TargetThreadWindows.cpp

@@ -17,7 +17,9 @@
 #include "ProcessWindows.h"
 #include "UnwindLLDB.h"
 
-#if !defined(_WIN64)
+#if defined(_WIN64)
+#include "x64/RegisterContextWindows_x64.h"
+#else
 #include "x86/RegisterContextWindows_x86.h"
 #endif
 
@@ -86,7 +88,7 @@ TargetThreadWindows::CreateRegisterContextForFrameIndex(uint32_t idx)
                 break;
             case llvm::Triple::x86_64:
 #if defined(_WIN64)
-                // FIXME: This is a 64-bit process, create a RegisterContextWindows_x86_64
+                m_reg_context_sp.reset(new RegisterContextWindows_x64(*this, idx));
 #else
                 // LLDB is 32-bit, but the target process is 64-bit.  We probably can't debug this.
 #endif