This replaces built-in os.MkdirAll with a patched version that stops the recursion
when reaching the volume part of the path. The original version would continue recursion,
and for extended length paths end up with \\? as the top-level directory, and the error
message would then be something like:
mkdir \\?: The filename, directory name, or volume label syntax is incorrect.
Before this patch selfupdate detected ANY build with cmount tag as a build
having libFUSE capabilities. However, only dynamic builds really have it.
The official linux builds are static and have the cmount tag as of the time
of this writing. This results in inability to update official linux binaries.
This patch fixes that. The build can be fixed independently.
