Add keywords for error reporting injection and case injection

[Liang2580]

chinese: 增加对报错注入的优化和对case的优化
English： Add keywords for error reporting injection and case injection

增加对 - 结尾的优化
Increase the optimization of - ending

As follows:
`static size_t parse_dash(struct libinjection_sqli_state * sf)
{
const char *cs = sf->s;
const size_t slen = sf->slen;
size_t pos = sf->pos;

/*

• five cases
• 1. --[white] this is always a SQL comment
• 2. --[EOF] this is a comment
• 3. --[notwhite] in MySQL this is NOT a comment but two unary operators
• 4. --[notwhite] everyone else thinks this is a comment
• 5. -[not dash] '-' is a unary operator
     */

if (pos + 2 == slen && cs[pos + 1] == '-' && char_is_white(cs[pos+2]) ) {
return parse_eol_comment(sf);
} else if (pos +2 == slen && cs[pos + 1] == '-') {
return parse_eol_comment(sf);
} else if (pos + 1 == slen && cs[pos + 1] == '-' && (sf->flags & FLAG_SQL_ANSI)) {
/* --[not-white] not-white case:
*
*/
sf->stats_comment_ddx += 1;
return parse_eol_comment(sf);
} else {
st_assign_char(sf->current, TYPE_OPERATOR, pos, 1, '-');
return pos + 1;
}
}`

[Liang2580]

Error injection test case：

and (select 1 from (select count(*),concat(user(),floor(rand(0)*2))x from information_schema.tables group by x)a); and (extractvalue(1,concat(0x7e,(select user()),0x7e))); and (updatexml(1,concat(0x7e,(select user()),0x7e),1)); and geometrycollection((select * from(select * from(select user())a)b)); and multipoint((select * from(select * from(select user())a)b)); and polygon((select * from(select * from(select user())a)b)); and multipolygon((select * from(select * from(select user())a)b)); and linestring((select * from(select * from(select user())a)b)); and multilinestring((select * from(select * from(select user())a)b)); and exp(~(select * from(select user())a));

case else test case
' or 1=case when current_user like 'dvwa%' then 1 else 3*1e08 end or 1=x'
'-1=x'