Fix for PR automake/285: * automake.in (handle_ltlibraries): Keep track of installation directories for each condition, then define a $(am_TARGET_rpath) variable to hold the -rpath flags of Libtool libraries conditionally installed in different directories. * lib/Automake/DisjConditions.pm (merge): New function. * tests/libtool6.test: Adjust. * tests/libtool8.test: New file. * tests/Makefile.am (TEST): Add libtool8.test.