Remove broken Cygwin path conversion.
* util/misc.c: [__CYGWIN__] Add include and define.
[__CYGWIN__] (get_win32_path): Copy function from getroot.c, modify
for Cygwin 1.7.
(make_system_path_relative_to_its_root): Simplify loop, replace early
return by break.
[__CYGWIN__] Add conversion to win32 path.
Include "/" case in trailing slash removal.