The configure check for ELF support in BFD uses the AC_TRY_LINK. If
libbfd's dependencies change, this macro will need to be updated
manually with explicit additions to LDFLAGS and LIBS.
This patch updates the check to use libtool instead.
ChangeLog:
* libctf/configure.ac: Use libtool instead.
* libctf/configure: Regenerated.