* som.h (som_copyable_section_data_struct): New structure

	* som.h (som_copyable_section_data_struct): New structure
	containing all the private section information which needs
	to be copied from input section to output section during
	objcopy or strip.
	(som_section_data_struct): Remove several fields now in
	som_copyable_section_data_struct.  Make the space and
	subspace dictionaries be pointers (to save space when
	only reading objects).

	* som.c (bfd_som_set_section_attributes): Now returns a boolean;
	some references changed.  Allocate a copyable data stucture if
	none exists.  Store info into the copyable data structure.
	(bfd_som_set_subsection_attributes): Likewise.
	(som_is_space, som_is_subspace, som_is_container): New functions.
	Use these instead of directly accessing private data.
	(som_prep_headers): Allocate space and subspace headers here.
	Fill in some fields in the space/subspace headers from the
	copyable data.
	(som_bfd_copy_private_section_data): Only copy the stuff
	that we really need to make objcopy and strip work.  Allocate
	the copy_data structure for the output bfd before copying.