Building with --disable-nls exposed many new warnings like these:
virsh.c:4952: warning: format not a string literal and no format ...
util.c:163: warning: format not a string literal and no format arguments
All but one of the following changes add a "%s" argument before
the offending _(...) argument.

This was the only manual change:
* src/lxc_driver.c (lxcVersion): Use %s and strerror(errno)
rather than %m, to avoid a warning from gcc -Wformat-security.

Add "%s" before each warned about format-string-with-no-%-directive:
* src/domain_conf.c (virDomainHostdevSubsysUsbDefParseXML)
(virDomainDefParseString, virDomainDefParseFile):
* src/hash.c (virGetConnect, __virGetDomain, virReleaseDomain)
(__virGetNetwork, virReleaseNetwork, __virGetStoragePool)
(virReleaseStoragePool, __virGetStorageVol, virReleaseStorageVol):
* src/lxc_container.c (lxcContainerChild):
* src/lxc_driver.c (lxcDomainDefine, lxcDomainUndefine)
(lxcDomainGetInfo, lxcGetOSType, lxcDomainDumpXML)
(lxcSetupInterfaces, lxcDomainStart, lxcDomainCreateAndStart)
(lxcVersion, lxcGetSchedulerParameters):
* src/network_conf.c (virNetworkDefParseString)
(virNetworkDefParseFile):
* src/openvz_conf.c (openvzReadNetworkConf, openvzLoadDomains):
* src/openvz_driver.c (openvzDomainDefineCmd)
(openvzDomainGetInfo, openvzDomainDumpXML, openvzDomainShutdown)
(openvzDomainReboot, ADD_ARG_LIT, openvzDomainDefineXML)
(openvzDomainCreateXML, openvzDomainCreate, openvzDomainUndefine)
(openvzDomainSetAutostart, openvzDomainGetAutostart)
(openvzDomainSetVcpus):
* src/qemu_driver.c (qemudDomainBlockPeek, qemudDomainMemoryPeek):
* src/remote_internal.c (remoteDomainBlockPeek)
(remoteDomainMemoryPeek, remoteAuthPolkit):
* src/sexpr.c (sexpr_new, _string2sexpr):
* src/storage_backend_disk.c (virStorageBackendDiskMakeDataVol)
(virStorageBackendDiskCreateVol):
* src/storage_backend_fs.c
(virStorageBackendFileSystemNetFindPoolSources):
* src/storage_backend_logical.c (virStorageBackendLogicalFindLVs)
(virStorageBackendLogicalFindPoolSources):
* src/test.c (testOpenDefault, testOpenFromFile, testOpen)
(testGetDomainInfo, testDomainRestore)
(testNodeGetCellsFreeMemory):
* src/util.c (virExec):
* src/virsh.c (cmdAttachDevice, cmdDetachDevice)
(cmdAttachInterface, cmdDetachInterface, cmdAttachDisk)
(cmdDetachDisk, cmdEdit):
* src/xend_internal.c (do_connect, wr_sync, xend_op_ext)
(urlencode, xenDaemonDomainCreateXML)
(xenDaemonDomainLookupByName_ids, xenDaemonDomainLookupByID)
(xenDaemonParseSxprOS, xend_parse_sexp_desc_char)
(xenDaemonParseSxprChar, xenDaemonParseSxprDisks)
(xenDaemonParseSxpr, sexpr_to_xend_topology, sexpr_to_domain)
(xenDaemonDomainFetch, xenDaemonDomainGetAutostart)
(xenDaemonDomainSetAutostart, xenDaemonDomainMigratePerform)
(xenDaemonDomainDefineXML, xenDaemonGetSchedulerType)
(xenDaemonGetSchedulerParameters)
(xenDaemonSetSchedulerParameters, xenDaemonDomainBlockPeek)
(xenDaemonFormatSxprChr, virDomainXMLDevID):
* src/xm_internal.c (xenXMConfigCacheRefresh, xenXMDomainPinVcpu)
(xenXMDomainCreate, xenXMDomainDefineXML)
(xenXMDomainAttachDevice, xenXMDomainDetachDevice):
* src/xml.c (virXPathString, virXPathNumber, virXPathLong)
(virXPathULong, virXPathBoolean, virXPathNode, virXPathNodeSet):
* src/xs_internal.c (xenStoreOpen):