storage: Revert volume obj list updating after volume creation (4749d82a)

This patch reverts commit 4749d82a which tried to tweak the logic in
volume creation. We did realloc and update our object list before we executed
volume building within a specific storage backend. If that failed, we
had to update (again) our object list to the original state as it was before the
build and delete the volume from the pool (even though it didn't exist - this
truly depends on the backend).
I misunderstood the base idea to be able to poll the status of the volume
creation using vol-info. After commit 4749d82a this wasn't possible
anymore, although no BZ has been reported yet.

Commit 4749d82a also claimed to fix
https://bugzilla.redhat.com/show_bug.cgi?id=1223177, but commit c8be606b of the
same series as 4749d82ad (which was more of a refactor than a fix)
fixes the same issue so the revert should be pretty straightforward.
Further more, BZ https://bugzilla.redhat.com/show_bug.cgi?id=1241454 can be
fixed with this revert.

src/storage/storage_driver.c

@@ -1803,6 +1803,9 @@ storageVolCreateXML(virStoragePoolPtr obj,
         goto cleanup;
     }
 
+    if (VIR_REALLOC_N(pool->volumes.objs,
+                      pool->volumes.count+1) < 0)
+        goto cleanup;
 
     if (!backend->createVol) {
         virReportError(VIR_ERR_NO_SUPPORT,
@@ -1817,6 +1820,14 @@ storageVolCreateXML(virStoragePoolPtr obj,
     if (backend->createVol(obj->conn, pool, voldef) < 0)
         goto cleanup;
 
+    pool->volumes.objs[pool->volumes.count++] = voldef;
+    volobj = virGetStorageVol(obj->conn, pool->def->name, voldef->name,
+                              voldef->key, NULL, NULL);
+    if (!volobj) {
+        pool->volumes.count--;
+        goto cleanup;
+    }
+
     if (VIR_ALLOC(buildvoldef) < 0) {
         voldef = NULL;
         goto cleanup;
@@ -1845,18 +1856,15 @@ storageVolCreateXML(virStoragePoolPtr obj,
         voldef->building = false;
         pool->asyncjobs--;
 
-        if (buildret < 0)
+        if (buildret < 0) {
+            VIR_FREE(buildvoldef);
+            storageVolDeleteInternal(volobj, backend, pool, voldef,
+                                     0, false);
+            voldef = NULL;
             goto cleanup;
-    }
-
-    if (VIR_REALLOC_N(pool->volumes.objs,
-                      pool->volumes.count+1) < 0)
-        goto cleanup;
+        }
 
-    pool->volumes.objs[pool->volumes.count++] = voldef;
-    if (!(volobj = virGetStorageVol(obj->conn, pool->def->name, voldef->name,
-                                    voldef->key, NULL, NULL)))
-        goto cleanup;
+    }
 
     if (backend->refreshVol &&
         backend->refreshVol(obj->conn, pool, voldef) < 0)