Update mkunicode.tcl to match the change erroneously made to machine generated file fts5_unicode2.c in [b7b7bde9].

FossilOrigin-Name: 326d579d777fdede6bc64f9525248767f4730de4e50260b0387e614a9d006416

ext/fts3/unicode/mkunicode.tcl

@@ -742,6 +742,7 @@ proc print_categories {lMap} {
         }
         iTbl++;
       }
+      aAscii[0] = 0;                  /* 0x00 is never a token character */
     }
   }]
 }