Create bcheck region for argv and arge argument

For program manipulating argv or arge as pointer with construct such as:

(while *argv++) {
  do_something_with_argv;
}

it is necessary to have argv and arge inside a region. This patch create
regions argv and arge) if main is declared with those parameters.

tcctok.h

@@ -237,6 +237,7 @@
      DEF(TOK___bound_ptr_indir8, "__bound_ptr_indir8")
      DEF(TOK___bound_ptr_indir12, "__bound_ptr_indir12")
      DEF(TOK___bound_ptr_indir16, "__bound_ptr_indir16")
+     DEF(TOK___bound_main_arg, "__bound_main_arg")
      DEF(TOK___bound_local_new, "__bound_local_new")
      DEF(TOK___bound_local_delete, "__bound_local_delete")
 # ifdef TCC_TARGET_PE