numatune: Fix parsing of empty nodeset (0,^0)

Resolves https://bugzilla.redhat.com/show_bug.cgi?id=1121837

src/util/virbitmap.c

@@ -378,6 +378,9 @@ virBitmapParse(const char *str,
         }
     }
 
+    if (virBitmapIsAllClear(*bitmap))
+        goto error;
+
     return virBitmapCountBits(*bitmap);
 
  error:

tests/qemuxml2argvdata/qemuxml2argv-numatune-memory-invalid-nodeset.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static' cpuset='0-1'>2</vcpu>
+  <numatune>
+    <memory mode="strict" nodeset="0,^0"/>
+  </numatune>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <cpu>
+    <topology sockets='2' cores='1' threads='1'/>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='ide' index='0'/>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1210,6 +1210,7 @@ mymain(void)
     DO_TEST("cputune-zero-shares", QEMU_CAPS_NAME);
 
     DO_TEST("numatune-memory", NONE);
+    DO_TEST_PARSE_ERROR("numatune-memory-invalid-nodeset", NONE);
     DO_TEST("numatune-memnode", QEMU_CAPS_NUMA, QEMU_CAPS_OBJECT_MEMORY_RAM);
     DO_TEST_FAILURE("numatune-memnode", NONE);