cachemissing required for proper operations (and related cases)

[cnettel]

Some eagerness and other flags might in fact be required for other flags. For example, eager rmdir and eager unlink have a prerequisite on inaccuratestat and cachemissing being turned on. Otherwise, getattr will return the true stat information for the backing filesystem. Since libfuse itself will do a getattr immediately following delete, this is disastrous (the existence of the file is then cached by libfuse, causing e.g. future new create operations on the same name to fail).