Don't canonicalize symlink targets; our win32 path canonicalization
routines expect an absolute path.  In particular, using the path
canonicalization routines for symlink targets (introduced in commit
7d55bee6, "win32: fix relative symlinks pointing into dirs",
2020-01-10).

Now, use the utf8 -> utf16 relative path handling functions, so that
paths like "../foo" will be translated to "..\foo".