virDomainMemoryDefParseXML: Don't leak discard

==1589== 7 bytes in 2 blocks are definitely lost in loss record 34 of 261
==1589==    at 0x4C2AF0F: malloc (vg_replace_malloc.c:299)
==1589==    by 0x8A82794: xmlStrndup (in /usr/lib64/libxml2.so.2.9.8)
==1589==    by 0x5DD8392: virXMLPropString (virxml.c:510)
==1589==    by 0x5E12427: virDomainMemoryDefParseXML (domain_conf.c:15704)
==1589==    by 0x5E207DE: virDomainDefParseXML (domain_conf.c:20351)
==1589==    by 0x5E2184F: virDomainDefParseNode (domain_conf.c:20636)
==1589==    by 0x5E216A1: virDomainDefParse (domain_conf.c:20580)
==1589==    by 0x5E21747: virDomainDefParseFile (domain_conf.c:20606)
==1589==    by 0x112F5F: testCompareXMLToArgv (qemuxml2argvtest.c:493)
==1589==    by 0x138780: virTestRun (testutils.c:180)
==1589==    by 0x117129: mymain (qemuxml2argvtest.c:937)
==1589==    by 0x13A83C: virTestMain (testutils.c:1120)
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NMarc Hartmayer <mhartmay@linux.ibm.com>

src/conf/domain_conf.c

@@ -15737,6 +15737,7 @@ virDomainMemoryDefParseXML(virDomainXMLOptionPtr xmlopt,
 
         def->discard = val;
     }
+    VIR_FREE(tmp);
 
     /* source */
     if ((node = virXPathNode("./source", ctxt)) &&