mv from strdup to qemu_strdup in qemu-option.c

one place is using strdup() instead of qemu_strdup

Fix it

Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/qemu-option.c b/qemu-option.c
index 61141e0..0473605 100644
--- a/qemu-option.c
+++ b/qemu-option.c
@@ -274,7 +274,7 @@
 
     case OPT_STRING:
         if (value != NULL) {
-            list->value.s = strdup(value);
+            list->value.s = qemu_strdup(value);
         } else {
             fprintf(stderr, "Option '%s' needs a parameter\n", name);
             return -1;
@@ -334,12 +334,12 @@
 
     while (cur && cur->name) {
         if (cur->type == OPT_STRING) {
-            free(cur->value.s);
+            qemu_free(cur->value.s);
         }
         cur++;
     }
 
-    free(list);
+    qemu_free(list);
 }
 
 /*