Use sizeof() instead of strlen().

mrbgems/mruby-bin-mirb/tools/mirb/mirb.c

@@ -106,7 +106,7 @@ is_code_block_open(struct mrb_parser_state *parser)
 
   /* check if parser error are available */
   if (0 < parser->nerr) {
-    const char *unexpected_end = "syntax error, unexpected $end";
+    const char unexpected_end[] = "syntax error, unexpected $end";
     const char *message = parser->error_buffer[0].message;
 
     /* a parser error occur, we have to check if */
@@ -114,7 +114,7 @@ is_code_block_open(struct mrb_parser_state *parser)
     /* a different issue which we have to show to */
     /* the user */
 
-    if (strncmp(message, unexpected_end, strlen(unexpected_end)) == 0) {
+    if (strncmp(message, unexpected_end, sizeof(unexpected_end) - 1) == 0) {
       code_block_open = TRUE;
     }
     else if (strcmp(message, "syntax error, unexpected keyword_end") == 0) {