* path.cc (path_conv::check): Optimize symlink replacements.

* path.cc (path_conv::check): Optimize symlink replacements.
* path.cc (normalize_posix_path): Add "tail" argument and set it.  Always have
a final slash for directories.  Pass 3rd argument to normalize_win32_path.
(path_conv::check): Pass tail to normalize_posix_path.  Set need_directory and
remove final slash after that call.  Remove last argument to
mount_table->conv_to_win32_path().  Remove noop dostail check.  Remove
fs.update() from inner loop.  Improve tail finding search.
(normalize_win32_path): Add and set tail argument.
(mount_item::build_win32): Avoid calling strcpy.
(mount_info::conv_to_win32_path): Remove third argument and simplify because
the source is normalized.  Keep /proc path in Posix form.  Call
win32_device_name() only once.
(mount_info::conv_to_posix_path): Add and use 3rd argument to
normalize_win32_path to avoid calling strlen.
(cwdstuff::set): Add 3rd argument to normalize_posix_path and remove final
slash if any.
* shared_info.h (mount_info::conv_to_win32_path): Remove last argument in
declaration.