make: fix GCC warnings

*** 38,47 ****
--- 38,49 ----
  #include <mksh/macro.h>
  #include <mksh/misc.h>          /* retmem() */
  #include <mksh/read.h>          /* get_next_block_fn() */
  #include <mksdmsi18n/mksdmsi18n.h>      /* libmksdmsi18n_init() */
  
+ #include <widec.h>
+ 
  /*
   * File table of contents
   */
  static void     add_macro_to_global_list(Name macro_to_add);
  #ifdef NSE
*** 862,872 ****
          Macro_list      new_macro;
          Macro_list      macro_on_list;
          char            *name_on_list = (char*)NULL;
          char            *name_to_add = macro_to_add->string_mb;
          char            *value_on_list = (char*)NULL;
!         char            *value_to_add = (char*)NULL;
  
          if (macro_to_add->prop->body.macro.value != NULL) {
                  value_to_add = macro_to_add->prop->body.macro.value->string_mb;
          } else {
                  value_to_add = "";
--- 864,874 ----
          Macro_list      new_macro;
          Macro_list      macro_on_list;
          char            *name_on_list = (char*)NULL;
          char            *name_to_add = macro_to_add->string_mb;
          char            *value_on_list = (char*)NULL;
!         const char      *value_to_add = (char*)NULL;
  
          if (macro_to_add->prop->body.macro.value != NULL) {
                  value_to_add = macro_to_add->prop->body.macro.value->string_mb;
          } else {
                  value_to_add = "";