libctf: installable libctf as a shared library

libctf: installable libctf as a shared library

This lets other programs read and write CTF-format data.

Two versioned shared libraries are created: libctf.so and
libctf-nobfd.so.  They contain identical content except that
libctf-nobfd.so contains no references to libbfd and does not implement
ctf_open, ctf_fdopen, ctf_bfdopen or ctf_bfdopen_ctfsect, so it can be
used by programs that cannot use BFD, like readelf.

The soname major version is presently .0 until the linker API
stabilizes, when it will flip to .1 and hopefully never change again.

New in v3.
v4: libtoolize and turn into a pair of shared libraries.  Drop
    --enable-install-ctf: now controlled by --enable-shared and
    --enable-install-libbfd, like everything else.
v5: Add ../bfd to ACLOCAL_AMFLAGS and AC_CONFIG_MACRO_DIR.  Fix tabdamage.

	* Makefile.def (host_modules): libctf is no longer no_install.
	* Makefile.in: Regenerated.
libctf/
	* configure.ac (AC_DISABLE_SHARED): New, like opcodes/.
	(LT_INIT): Likewise.
	(AM_INSTALL_LIBBFD): Likewise.
	(dlopen): Note why this is necessary in a comment.
	(SHARED_LIBADD): Initialize for possibly-PIC libiberty: derived from
	opcodes/.
	(SHARED_LDFLAGS): Likewise.
	(BFD_LIBADD): Likewise, for libbfd.
	(BFD_DEPENDENCIES): Likewise.
	(VERSION_FLAGS): Initialize, using a version script if ld supports
	one, or libtool -export-symbols-regex otherwise.
	(AC_CONFIG_MACRO_DIR): Add ../BFD.
	* Makefile.am (ACLOCAL_AMFLAGS): Likewise.
	(INCDIR): New.
	(AM_CPPFLAGS): Use $(srcdir), not $(top_srcdir).
	(noinst_LIBRARIES): Replace with...
	[INSTALL_LIBBFD] (lib_LTLIBRARIES): This, or...
	[!INSTALL_LIBBFD] (noinst_LTLIBRARIES): ... this, mentioning new
	libctf-nobfd.la as well.
	[INSTALL_LIBCTF] (include_HEADERS): Add the CTF headers.
	[!INSTALL_LIBCTF] (include_HEADERS): New, empty.
	(libctf_a_SOURCES): Rename to...
	(libctf_nobfd_la_SOURCES): ... this, all of libctf other than
	ctf-open-bfd.c.
	(libctf_la_SOURCES): Now derived from libctf_nobfd_la_SOURCES,
	with ctf-open-bfd.c added.
	(libctf_nobfd_la_LIBADD): New, using @SHARED_LIBADD@.
	(libctf_la_LIBADD): New, using @BFD_LIBADD@ as well.
	(libctf_la_DEPENDENCIES): New, using @BFD_DEPENDENCIES@.
	* Makefile.am [INSTALL_LIBCTF]: Use it.
	* aclocal.m4: Add ../bfd/acinclude.m4, ../config/acx.m4, and the
	libtool macros.
	* libctf.ver: New, everything is version LIBCTF_1.0 currently (even
	the unstable components).
	* Makefile.in: Regenerated.
	* config.h.in: Likewise.
	* configure: Likewise.
binutils/
	* Makefile.am (LIBCTF): Mention the .la file.
	(LIBCTF_NOBFD): New.
	(readelf_DEPENDENCIES): Use it.
	(readelf_LDADD): Likewise.
	* Makefile.in: Regenerated.
ld/
	* configure.ac (TESTCTFLIB): Set to the .so or .a, like TESTBFDLIB.
	* Makefile.am (TESTCTFLIB): Use it.
	(LIBCTF): Use the .la file.
	(check-DEJAGNU): Use it.
	* Makefile.in: Regenerated.
	* configure: Likewise.
include/
	* ctf-api.h: Note the instability of the ctf_link interfaces.