Fix race condition in macFUSE.framework that was introduced in version 4.8.2. The race condition can be triggered by removing items from a directory while listing the directory's contents. This can lead to a segmentation fault.

Improve fault tolerance of installer and uninstaller. There are documented cases of pkgutil(1) returning invalid version numbers for installed packages. This could result in issues when installing macFUSE updates or running the uninstaller.

Work around a bug in xcodebuild resulting in SDKs being listed twice.