Really fix XML formatting flags in SaveImageUpdateDef

Commit cf2d4c6 used a logical or instead of bitwise or,
effectively passing 1, that is VIR_DOMAIN_XML_INACTIVE.

This was caught by a warning when building with clang.

https://bugzilla.redhat.com/show_bug.cgi?id=1183869

src/qemu/qemu_driver.c

@@ -5734,7 +5734,7 @@ qemuDomainSaveImageUpdateDef(virQEMUDriverPtr driver,
 
     if (!(newdef_migr = qemuDomainDefCopy(driver,
                                           newdef,
-                                          QEMU_DOMAIN_FORMAT_LIVE_FLAGS ||
+                                          QEMU_DOMAIN_FORMAT_LIVE_FLAGS |
                                           VIR_DOMAIN_XML_MIGRATABLE)))
         goto cleanup;