Merge of r4674, r4675, r4676: win32 fixes.

Merge of r4674, r4675, r4676: win32 fixes.

*) Win32: disallowed access to various non-canonical name variants.

   This includes trailings dots and spaces, NTFS streams (and short names, as
   previously checked).  The checks are now also done in ngx_file_info(), thus
   allowing to use the "try_files" directive to protect external scripts.

*) Win32: normalization of trailing dot inside uri.

   Windows treats "/directory./" identical to "/directory/".  Do the same
   when working on Windows.  Note that the behaviour is different from one
   with last path component (where multiple spaces and dots are ignored by
   Windows).

*) Win32: uris with ":$" are now rejected.

   There are too many problems with special NTFS streams, notably "::$data",
   "::$index_allocation" and ":$i30:$index_allocation".

   For now we don't reject all URIs with ":" like Apache does as there are no
   good reasons seen yet, and there are multiple programs using it in URLs
   (e.g. MediaWiki).