splitstatement support optimizer hint

  https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html
  https://dev.mysql.com/doc/refman/8.0/en/comments.html

ast/testdata/TestSplitStatement.golden

@@ -36,6 +36,8 @@ where col = 1
 tb;
 18 
 -- comment
+19 INSERT /*+ SET_VAR(foreign_key_checks=OFF) */ INTO t2 VALUES(2);
+20 select /*!50000 1,*/ 1;
 0 select * from test\Ghello
 1 select 'hello\Gworld', col from test\Ghello
 2 -- select * from test\Ghello

ast/token.go

@@ -898,8 +898,11 @@ func SplitStatement(buf []byte, delimiter []byte) (string, string, []byte) {
 		}
 
 		// multi line comment
+		// https://dev.mysql.com/doc/refman/8.0/en/comments.html
+		// https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html
 		if b == '/' && i+1 < len(buf) && buf[i+1] == '*' {
-			if !multiLineComment && !singleLineComment && !quoted && buf[i+2] != '!' {
+			if !multiLineComment && !singleLineComment && !quoted &&
+				(buf[i+2] != '!' && buf[i+2] != '+') {
 				i = i + 2
 				multiLineComment = true
 				continue

ast/token_test.go

@@ -166,6 +166,8 @@ select col from tb where col = 1;`),
 select col from tb;
 select col from tb;
 `),
+		[]byte(`INSERT /*+ SET_VAR(foreign_key_checks=OFF) */ INTO t2 VALUES(2);`),
+		[]byte(`select /*!50000 1,*/ 1;`),
 	}
 	buf2s := [][]byte{
 		[]byte("select * from test\\Ghello"),