libctf: fix a number of build problems found on Solaris and NetBSD

libctf: fix a number of build problems found on Solaris and NetBSD

- Use of nonportable <endian.h>
- Use of qsort_r
- Use of zlib without appropriate magic to pull in the binutils zlib
- Use of off64_t without checking (fixed by dropping the unused fields
  that need off64_t entirely)
- signedness problems due to long being too short a type on 32-bit
  platforms: ctf_id_t is now 'unsigned long', and CTF_ERR must be
  used only for functions that return ctf_id_t
- One lingering use of bzero() and of <sys/errno.h>

All fixed, using code from gnulib where possible.

Relatedly, set cts_size in a couple of places it was missed
(string table and symbol table loading upon ctf_bfdopen()).

binutils/
	* objdump.c (make_ctfsect): Drop cts_type, cts_flags, and
	cts_offset.
	* readelf.c (shdr_to_ctf_sect): Likewise.
include/
	* ctf-api.h (ctf_sect_t): Drop cts_type, cts_flags, and cts_offset.
	(ctf_id_t): This is now an unsigned type.
	(CTF_ERR): Cast it to ctf_id_t.  Note that it should only be used
	for ctf_id_t-returning functions.
libctf/
	* Makefile.am (ZLIB): New.
	(ZLIBINC): Likewise.
	(AM_CFLAGS): Use them.
	(libctf_a_LIBADD): New, for LIBOBJS.
	* configure.ac: Check for zlib, endian.h, and qsort_r.
	* ctf-endian.h: New, providing htole64 and le64toh.
	* swap.h: Code style fixes.
	(bswap_identity_64): New.
	* qsort_r.c: New, from gnulib (with one added #include).
	* ctf-decls.h: New, providing a conditional qsort_r declaration,
	and unconditional definitions of MIN and MAX.
	* ctf-impl.h: Use it.  Do not use <sys/errno.h>.
	(ctf_set_errno): Now returns unsigned long.
	* ctf-util.c (ctf_set_errno): Adjust here too.
	* ctf-archive.c: Use ctf-endian.h.
	(ctf_arc_open_by_offset): Use memset, not bzero.  Drop cts_type,
	cts_flags and cts_offset.
	(ctf_arc_write): Drop debugging dependent on the size of off_t.
	* ctf-create.c: Provide a definition of roundup if not defined.
	(ctf_create): Drop cts_type, cts_flags and cts_offset.
	(ctf_add_reftype): Do not check if type IDs are below zero.
	(ctf_add_slice): Likewise.
	(ctf_add_typedef): Likewise.
	(ctf_add_member_offset): Cast error-returning ssize_t's to size_t
	when known error-free.  Drop CTF_ERR usage for functions returning
	int.
	(ctf_add_member_encoded): Drop CTF_ERR usage for functions returning
	int.
	(ctf_add_variable): Likewise.
	(enumcmp): Likewise.
	(enumadd): Likewise.
	(membcmp): Likewise.
	(ctf_add_type): Likewise.  Cast error-returning ssize_t's to size_t
	when known error-free.
	* ctf-dump.c (ctf_is_slice): Drop CTF_ERR usage for functions
	returning int: use CTF_ERR for functions returning ctf_type_id.
	(ctf_dump_label): Likewise.
	(ctf_dump_objts): Likewise.
	* ctf-labels.c (ctf_label_topmost): Likewise.
	(ctf_label_iter): Likewise.
	(ctf_label_info): Likewise.
	* ctf-lookup.c (ctf_func_args): Likewise.
	* ctf-open.c (upgrade_types): Cast to size_t where appropriate.
	(ctf_bufopen): Likewise.  Use zlib types as needed.
	* ctf-types.c (ctf_member_iter): Drop CTF_ERR usage for functions
	returning int.
	(ctf_enum_iter): Likewise.
	(ctf_type_size): Likewise.
	(ctf_type_align): Likewise.  Cast to size_t where appropriate.
	(ctf_type_kind_unsliced): Likewise.
	(ctf_type_kind): Likewise.
	(ctf_type_encoding): Likewise.
	(ctf_member_info): Likewise.
	(ctf_array_info): Likewise.
	(ctf_enum_value): Likewise.
	(ctf_type_rvisit): Likewise.
	* ctf-open-bfd.c (ctf_bfdopen): Drop cts_type, cts_flags and
	cts_offset.
	(ctf_simple_open): Likewise.
	(ctf_bfdopen_ctfsect): Likewise.  Set cts_size properly.
	* Makefile.in: Regenerate.
	* aclocal.m4: Likewise.
	* config.h: Likewise.
	* configure: Likewise.