libs/libc/stdio: using sprintf to instead itoa

itoa isn't posix function, the standard stdlib file exclude it.

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>

libs/libc/stdio/lib_libbsprintf.c

@@ -164,7 +164,7 @@ int lib_bsprintf(FAR struct lib_outstream_s *s, FAR const IPTR char *fmt,
         }
       else if (c == '*')
         {
-          itoa(var->i, fmtstr + len - 1, 10);
+          sprintf(fmtstr + len - 1, "%d", var->i);
           len = strlen(fmtstr);
           offset += sizeof(var->i);
         }