To avoid a namespace clash with forthcoming identity APIs,
rename the virNet*GetLocalIdentity() APIs to have the form
virNet*GetUNIXIdentity()

* daemon/remote.c, src/libvirt_private.syms: Update
  for renamed APIs
* src/rpc/virnetserverclient.c, src/rpc/virnetserverclient.h,
  src/rpc/virnetsocket.c, src/rpc/virnetsocket.h: s/LocalIdentity/UNIXIdentity/