livepatch-build: Strip transient or unneeded symbols
In the process of creating a final hotpatch module file make sure to
strip all transient symbols that have not been caught and removed by
create-diff-object processing. For now these are only the hooks
kpatch load/unload symbols.
For all new object files that are carried along for the final linking
the transient hooks symbols are not stripped and neither are any
unneeded symbols. Strip them explicitly from resulting object file.