dbghelp: ensure the DLL from our executable directory is loaded (avoids
breakage related to search-path and Dropbox)
wmi: use single-thread apartment COM model because multithreaded breaks
SHGetFolderPathW
wsysdep: sys_pick_directory: allow user-specified initial path; fix
previous non-unicode initial path; avoid reporting error if user cancels
wutil: add function to query executable directory at any time
This was SVN commit r7633.