The C reproducers generated by gcc_jit_context_dump_reproducer_to_file
contain numerous pointer values (from %p) to ensure uniqueness of the
identifiers, but this makes them less readable than they could be.

This patch updates reproducer::make_identifier so that the pointer
is only added if it's necessary for uniqueness.

gcc/jit/ChangeLog:
	* jit-recording.c (class gcc::jit::reproducer): Rename field
	"m_identifiers" to "m_map_memento_to_identifier".  Add field
	"m_set_identifiers" and struct hash_traits for it.
	(gcc::jit::reproducer::reproducer): Update for above.
	(convert_to_identifier): New function.
	(gcc::jit::reproducer::ensure_identifier_is_unique): New method.
	(gcc::jit::reproducer::make_identifier): Avoid appending the %p
	unless necessary for uniqueness.  Update for field renaming.
	(gcc::jit::reproducer::get_identifier): Update for field renaming.

From-SVN: r251191