Ensure libsvn_fs_x_LDFLAGS ends up in the Makefile so that flags such as -Wl,--no-undefined can be passed to the FSX library just as they are for the other Subversion libraries. The configure script was already setting libsvn_fs_x_LDFLAGS but it was not propagated to the Makefile. * Makefile.in: Add libsvn_fs_x_LDFLAGS. * configure.ac: Substitute libsvn_fs_x_LDFLAGS.