An additional fix for WL#1213 4-byte UTF8

- Fixing crash on attempt to create a fulltext index with an utf8mb4 column
- fixing wrong border width  for supplementary characters in mysql client:

  mysql --default-character-set=utf8mb4 -e "select concat(_utf32 0x20000,'a')"

mysql-test/r/ctype_utf8mb4.result

@@ -2438,6 +2438,9 @@ t1	CREATE TABLE `t1` (
 INSERT INTO t1(subject) VALUES ('abcd');
 INSERT INTO t1(subject) VALUES(x'f0909080');
 DROP TABLE t1;
+CREATE TABLE t1 (a TEXT CHARACTER SET utf8mb4, FULLTEXT INDEX(a));
+INSERT INTO t1 VALUES (0xF0A08080 /* U+20000 */ );
+DROP TABLE t1;
 #
 # Bug #51676 Server crashes on SELECT, ORDER BY on 'utf8mb4' column
 #

mysql-test/t/ctype_utf8mb4.test

@@ -1763,6 +1763,13 @@ INSERT INTO t1(subject) VALUES ('abcd');
 INSERT INTO t1(subject) VALUES(x'f0909080');
 DROP TABLE t1;
 
+#
+# Make sure fulltext does not crash on supplementary characters
+#
+CREATE TABLE t1 (a TEXT CHARACTER SET utf8mb4, FULLTEXT INDEX(a));
+INSERT INTO t1 VALUES (0xF0A08080 /* U+20000 */ );
+DROP TABLE t1;
+
 --echo #
 --echo # Bug #51676 Server crashes on SELECT, ORDER BY on 'utf8mb4' column
 --echo #

strings/ctype-mb.c

@@ -1123,8 +1123,16 @@ size_t my_numcells_mb(CHARSET_INFO *cs, const char *b, const char *e)
       continue;
     }
     b+= mb_len;
-    pg= (wc >> 8) & 0xFF;
-    clen+= utr11_data[pg].p ? utr11_data[pg].p[wc & 0xFF] : utr11_data[pg].page;
+    if (wc > 0xFFFF)
+    {
+      if (wc >= 0x20000 && wc <= 0x3FFFD) /* CJK Ideograph Extension B, C */
+        clen+= 1;
+    }
+    else
+    {
+      pg= (wc >> 8) & 0xFF;
+      clen+= utr11_data[pg].p ? utr11_data[pg].p[wc & 0xFF] : utr11_data[pg].page;
+    }
     clen++;
   }
   return clen;
@@ -1136,7 +1144,7 @@ int my_mb_ctype_mb(CHARSET_INFO *cs, int *ctype,
 {
   my_wc_t wc;
   int res= cs->cset->mb_wc(cs, &wc, s, e);
-  if (res <= 0)
+  if (res <= 0 || wc > 0xFFFF)
     *ctype= 0;
   else
     *ctype= my_uni_ctype[wc>>8].ctype ?