In function lib/util_str.c/struppter_m() and strlower_m(), almost execute slow 
path. almost never fast path. 

I think while loop condition,
   --------------------------------------------------
    while (*s && !(((unsigned char)s[0]) & 0x7F)) { 
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   --------------------------------------------------
is wrong. 

below code is correct?
   --------------------------------------------------
    while (*s && (((unsigned char)s[0]) <= 0x7F)) { 
   --------------------------------------------------

-------------------------------------------------------------------------
void strlower_m(char *s)
{
    /* this is quite a common operation, so we want it to be
       fast. We optimise for the ascii case, knowing that all our
       supported multi-byte character sets are ascii-compatible
       (ie. they match for the first 128 chars) */

    while (*s && !(((unsigned char)s[0]) & 0x7F)) { <---#### this ####
        *s = tolower((unsigned char)*s);
        s++;
    }

    if (!*s)
        return;

    /* I assume that lowercased string takes the same number of bytes
     * as source string even in UTF-8 encoding. (VIV) */
    unix_strlower(s,strlen(s)+1,s,strlen(s)+1);    
}
-------------------------------------------------------------------------