Win32: Set errno to ENAMETOOLONG when os_stat() returns -1.

Win32: Set errno to ENAMETOOLONG when os_stat() returns -1.

This will fix problem where Apache on Windows can return a directory index when
it should return a negotiated file.  read_types_multi() iterates over
the entries in a directory to build a candidate list of
files to negotiate.  ap_sub_req_lookup_file() is called for each file
which in turn calls stat() (os_stat() on Windows) to verify the file exists.
mod_negotiation will decline the request (rather than failing the
request as it should) if os_stat() fails and errno is not set.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@91150 13f79535-47bb-0310-9956-ffa450edef68