Commit 35998fc2fa6cbb7d761f6d88346246bd3627552b fixed the buffer underun
in win32 path normalization, but introduced a new bug: A wrong
assumption led to the inability to backtrack the path outside of the
current working directory in case of relative paths.
This patch fixes this problem, together with a minor problem if the CWD
is on a network share: The result erroneously started with tripple
backslash if the src path starts with a single backslash.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
