in cases where the memorized match range from the right factor
exceeded the length of the left factor, it was wrongly treated as a
mismatch rather than a match.
issue reported by Yves Bastide.
to deal with the fact that the public headers may be used with pre-c99
compilers, __restrict is used in place of restrict, and defined
appropriately for any supported compiler. we also avoid the form
[restrict] since older versions of gcc rejected it due to a bug in the
original c99 standard, and instead use the form *restrict.
since this interface is rarely used, it's probably best to lean
towards keeping code size down anyway. one-character needles will
still be found immediately by the initial wcschr call anyway.
