stristr and findiStr with SSE4.2

I made a function stristr() same as strcasestr() and findiStr(), which is ranged version of stristr(). These functions use SSE4.2 string instructions and three times faster than strcasestr() of glibc. The souce code is https://github.com/herumi/opti/blob/master/str_util.hpp. Please see Quick search algorithm and strstr.