libctf: rip out BFD_DEPENDENCIES / BFD_LIBADD

libctf: rip out BFD_DEPENDENCIES / BFD_LIBADD

This complex morass inherited from libopcodes, which endeavours to
implement the effect of specifying ../bfd/libbfd.la in _LIBADD without
actually doing so, appears to be working around a libtool bug which as
far as I can see is no longer present (i.e., the install directory no
longer appears in -L arguments in libtool link-mode invocations, so
there is no danger of picking up old libbfds or other dependent
libraries).

Replaced with a simple reference to libbfd.la in the appropriate place.
Also adjusted things a little more so that libctf.la and libctf-nobfd.la
are self-contained, even when linking statically.  This opens up the
possibility of running libtool to link against libctf from inside the
(upcoming) testsuite.

libctf/ChangeLog
2021-01-05  Nick Alcock  <nick.alcock@oracle.com>

	* configure.ac (BFD_LIBADD): Remove.
	(BFD_DEPENDENCIES): Likewise. Remove associated cases.
	(SHARED_LIBADD): Rename to...
	(CTF_LIBADD): ... this.  Stick in a suitable libiberty even when
	linking statically.
	* Makefile.am (libctf_nobfd_la_LIBADD): Adjust accordingly.
	libctf uses libintl.
	(libctf_la_LIBADD): Reference libbfd.la directly, not via
	BFD_LIBADD.
	(libctf_la_DEPENDENCIES): Remove.
	* Makefile.in: Regenerate.
	* configure: Likewise.