Replace virNWFilterFree with virObjectUnref

Since virNWFilterFree will call virObjectUnref anyway, let's just use that
directly so as to avoid the possibility that we inadvertently clear out
a pending error message when using the public API.

cfg.mk

@@ -992,7 +992,7 @@ sc_prohibit_system_error_with_vir_err:
 # functions. There's a corresponding exclude to allow usage within tests,
 # docs, examples, tools, src/libvirt-*.c, and include/libvirt/libvirt-*.h
 sc_prohibit_virXXXFree:
-	@prohibit='\bvir(Domain|Network|NodeDevice|StorageVol|StoragePool|Stream|Secret)Free\b'	\
+	@prohibit='\bvir(Domain|Network|NodeDevice|StorageVol|StoragePool|Stream|Secret|NWFilter)Free\b'	\
 	exclude='sc_prohibit_virXXXFree' \
 	halt='avoid using 'virXXXFree', use 'virObjectUnref' instead' \
 	  $(_sc_search_regexp)
@@ -1186,4 +1186,4 @@ exclude_file_name_regexp--sc_prohibit_devname = \
   ^(tools/virsh.pod|cfg.mk|docs/.*)$$
 
 exclude_file_name_regexp--sc_prohibit_virXXXFree = \
-  ^(docs/|tests/|examples/|tools/|cfg.mk|src/test/test_driver.c|src/libvirt_public.syms|include/libvirt/libvirt-(domain|network|nodedev|storage|stream|secret).h|src/libvirt-(domain|qemu|network|nodedev|storage|stream|secret).c$$)
+  ^(docs/|tests/|examples/|tools/|cfg.mk|src/test/test_driver.c|src/libvirt_public.syms|include/libvirt/libvirt-(domain|network|nodedev|storage|stream|secret|nwfilter).h|src/libvirt-(domain|qemu|network|nodedev|storage|stream|secret|nwfilter).c$$)

daemon/remote.c

@@ -4964,7 +4964,7 @@ remoteDispatchConnectListAllNWFilters(virNetServerPtr server ATTRIBUTE_UNUSED,
         virNetMessageSaveError(rerr);
     if (filters && nfilters > 0) {
         for (i = 0; i < nfilters; i++)
-            virNWFilterFree(filters[i]);
+            virObjectUnref(filters[i]);
         VIR_FREE(filters);
     }
     return rv;

src/nwfilter/nwfilter_driver.c

@@ -547,10 +547,8 @@ nwfilterConnectListAllNWFilters(virConnectPtr conn,
  cleanup:
     nwfilterDriverUnlock(driver);
     if (tmp_filters) {
-        for (i = 0; i < nfilters; i ++) {
-            if (tmp_filters[i])
-                virNWFilterFree(tmp_filters[i]);
-        }
+        for (i = 0; i < nfilters; i ++)
+            virObjectUnref(tmp_filters[i]);
     }
     VIR_FREE(tmp_filters);
 

src/remote/remote_driver.c

@@ -3452,8 +3452,7 @@ remoteConnectListAllNWFilters(virConnectPtr conn,
  cleanup:
     if (tmp_filters) {
         for (i = 0; i < ret.filters.filters_len; i++)
-            if (tmp_filters[i])
-                virNWFilterFree(tmp_filters[i]);
+            virObjectUnref(tmp_filters[i]);
         VIR_FREE(tmp_filters);
     }