Disallow:
 1. paths with trailing dot
 2. paths with trailing space
 3. paths with trailing colon
 4. paths that are 8.3 short names of .git folders ("GIT~1")
 5. paths that are reserved path names (COM1, LPT1, etc).
 6. paths with reserved DOS characters (colons, asterisks, etc)

These paths would (without \\?\ syntax) be elided to other paths - for
example, ".git." would be written as ".git".  As a result, writing these
paths literally (using \\?\ syntax) makes them hard to operate with from
the shell, Windows Explorer or other tools.  Disallow these.