esx: Report error in esxVI_LookupVirtualMachineByName

When reviewing 00d9edfe I've changed proposed patch and
made it to not report error if no domain is found. This is wrong
and the original patch was okay. Thing is, both callers pass
occurrence = OptionalItem so no error message overwriting is done
as I thought initially.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

src/esx/esx_vi.c

@@ -3014,8 +3014,11 @@ esxVI_LookupVirtualMachineByName(esxVI_Context *ctx, const char *name,
         break;
     }
 
-    if (!(*virtualMachine) && occurrence != esxVI_Occurrence_OptionalItem)
+    if (!(*virtualMachine) && occurrence != esxVI_Occurrence_OptionalItem) {
+        virReportError(VIR_ERR_NO_DOMAIN,
+                       _("Could not find domain with name '%s'"), name);
         goto cleanup;
+    }
 
     result = 0;