tests: teach syntax-check that virDomainDefFree has free-like semantics

* cfg.mk (useless_free_options): Add virDomainDefFree to the list
of free-like functions.
* src/test/test_driver.c (testDomainCreateXML): Remove useless-if-
before-virDomainDefFree.
* src/conf/domain_conf.c (virDomainAssignDef): Likewise

cfg.mk

@@ -64,6 +64,7 @@ useless_free_options =		\
   --name=VIR_FREE		\
   --name=xmlFree		\
   --name=xmlXPathFreeContext	\
+  --name=virDomainDefFree	\
   --name=xmlXPathFreeObject
 
 # Avoid uses of write(2).  Either switch to streams (fwrite), or use

src/conf/domain_conf.c

@@ -759,8 +759,7 @@ virDomainObjPtr virDomainAssignDef(virCapsPtr caps,
             virDomainDefFree(domain->def);
             domain->def = def;
         } else {
-            if (domain->newDef)
-                virDomainDefFree(domain->newDef);
+            virDomainDefFree(domain->newDef);
             domain->newDef = def;
         }
 

src/test/test_driver.c

@@ -1328,8 +1328,7 @@ cleanup:
         virDomainObjUnlock(dom);
     if (event)
         testDomainEventQueue(privconn, event);
-    if (def)
-        virDomainDefFree(def);
+    virDomainDefFree(def);
     testDriverUnlock(privconn);
     return ret;
 }