MXS-1196: Accept :'a' as placeholder variables

Oracle SQL accepts statements like

  PREPARE stmt FROM 'INSERT INTO t1 VALUES (:a,:b)';
  PREPARE stmt FROM 'INSERT INTO t1 VALUES (:"a",:"b")';

That is, the variable may be surrounded by quotes.

query_classifier/qc_sqlite/sqlite-src-3110100/src/tokenize.c

@@ -496,6 +496,20 @@ int sqlite3GetToken(const unsigned char *z, int *tokenType){
           break;
         }else if( c==':' && z[i+1]==':' ){
           i++;
+#endif
+#ifdef MAXSCALE
+        }else if ( c=='\'' || c=='"' || c=='`' ){
+          int q=c;
+          ++i;
+          while ( IdChar(z[i]) ) {
+            ++i;
+            ++n;
+          }
+          if ( z[i]==q )
+          {
+            ++i;
+            break;
+          }
 #endif
         }else{
           break;