Support for building bfd and opcodes as shared libraries, based on
patches from Alan Modra <alan@spri.levels.unisa.edu.au>:
* configure.in: Set OPCODES and BFD to search directories.
Substitute OPCODES_DEP and BFDDEP. On SunOS, set HLDFLAGS.
* configure: Rebuild.
* Makefile.in (LDFLAGS, HLDFLAGS): New variables.
(LIBDEPS): New variable.
(as.new0: Depend upon $(LIBDEPS) rather than $(LIBS). Use
$(HLDFLAGS) in link.
(check): Set LD_LIBRARY_PATH in the environment.