libtcc.c (put_extern_sym2): Extend the scope of buf to match its use

After leaving the code block that `buf' is defined, `buf' will not
exist, so `name' will point to a variable that does not exist.

libtcc.c

@@ -459,9 +459,8 @@ ST_FUNC void put_extern_sym2(Sym *sym, Section *section,
     if (!sym->c) {
         name = get_tok_str(sym->v, NULL);
 #ifdef CONFIG_TCC_BCHECK
+        char buf[32];
         if (tcc_state->do_bounds_check) {
-            char buf[32];
-
             /* XXX: avoid doing that for statics ? */
             /* if bound checking is activated, we change some function
                names by adding the "__bound" prefix */