TESTS: fix problem(s) with the (installed) test binaries for lib*.so

* What: reported by R. Machado and M. Kuhn, no possibility to debug
and/or run test from installation directory, respectively
* When: shared libraries compilation
* By: the tests binaries are now considered
in the actual autoconf/libtool installation process.
* But: the microbenchmarks are now installed in its own bin/ directory