Change the default behaviour of the PE targeted linker so that timestamps are

Change the default behaviour of the PE targeted linker so that timestamps are
inserted.  This is for compatibility with other, non-GNU tools.  Deterministic
binaries can still be created by using the new --no-insert-timestamp command line
option.

	* emultempl/pe.em: Initialise insert_timestamp to true.
	Add a --no-insert-timestamp command line option.
	* emultempl/pep.em: Likewise.
	* ld.texinfo: Document that --insert-timestamp is enabled by
	default and that it now has an inverse command line option.
	* NEWS: Mention the new behaviour.