To date, libiberty is generally not installed on its own. It has evolved
over years but does not have its own version number nor release schedule.
Possibly the easiest way to use libiberty in your projects is to drop the
libiberty code into your project's sources, and to build the library along
with your own sources; the library would then be linked in at the end. This
prevents any possible version mismatches with other copies of libiberty
elsewhere on the system.
Passing --enable-install-libiberty to the configure
script when building libiberty causes the header files and archive library
to be installed when make install is run. This option also takes
an (optional) argument to specify the installation location, in the same
manner as --prefix.
For your own projects, an approach which offers stability and flexibility
is to include libiberty with your code, but allow the end user to optionally
choose to use a previously-installed version instead. In this way the
user may choose (for example) to install libiberty as part of GCC, and use
that version for all software built with that compiler. (This approach
has proven useful with software using the GNU readline library.)
Making use of libiberty code usually requires that you include one or more
header files from the libiberty distribution. (They will be named as
necessary in the function descriptions.) At link time, you will need to
add -liberty to your link command invocation.