* dir.cc (readdir): Use strcasematch for consistency.

* dir.cc (readdir): Use strcasematch for consistency.
* path.cc (symlink_info): Eliminate known_suffix.
(path_conv::check): Always copy ext_here to end of buffer, if found.
(suffix_scan): Eliminate ext_here, add suffixes_start.
(suffix_scan::has): Eliminate an argument.  Reorganize.  Always return pointer
to end of input path.
(suffix_scan::next): Take a second pass through the suffix list looking for
.lnk.
(symlink_info::check): Eliminate known_suffix usage.