win64 "patch"

Seems win64 almost works fine out of the box. 1 minor thing is needed:

diff --git a/source/Plugins/Process/Windows/Common/x64/RegisterContextWindows_x64.cpp b/source/Plugins/Process/Windows/Common/x64/RegisterContextWindows_x64.cpp
index 103cff4..4b37c3f 100644

Looks good.