File::Find: support Win32 symlinks

File::Find: support Win32 symlinks

find.t, taint.t: check that symlink() works under the current
permissions/filesystem rather than assuming it will work

find.t: since symlinks are now available, an earlier test block
set $FileFileTests_OK, and the tests in this Win32 block don't use
either of the follow options, which is required for fast file tests.

taint.t: ensure we get "/" separated names to match File::Find's output