Convert some malloc + strncpy pairs into strndup calls

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Jeremy Huddleston <jeremyhu@apple.com>

hw/kdrive/src/kinput.c

@@ -1049,12 +1049,10 @@ KdGetOptions (InputOption **options, char *string)
     if (strchr(string, '='))
     {
         tam_key = (strchr(string, '=') - string);
-        key = malloc(tam_key + 1);
+        key = strndup(string, tam_key);
         if (!key)
             goto out;
 
-        strncpy(key, string, tam_key);
-        key[tam_key] = '\0';
         value = strdup(strchr(string, '=') + 1);
         if (!value)
             goto out;