xen-xm: SIGSEGV in xenXMDomainDefineXML: filename

filename is not initialized to NULL while it's unconditionally freed in
the error path.

Signed-off-by: Philipp Hahn <hahn@univention.de>

src/xen/xm_internal.c

@@ -1070,7 +1070,7 @@ int xenXMDomainCreate(virDomainPtr domain) {
 virDomainPtr xenXMDomainDefineXML(virConnectPtr conn, const char *xml)
 {
     virDomainPtr ret;
-    char *filename;
+    char *filename = NULL;
     const char *oldfilename;
     virDomainDefPtr def = NULL;
     virConfPtr conf = NULL;