Fix a compilation issue and configure tests. The LDFLAGS and CPPFLAGS were not set properly after a configure. A Makefile was not generated in the src/bench directory. * ../build-aux/vcsn-boost.m4: Set LDFLAGS and CPPFLAGS correctly. * ../build-aux/vcsn-xml.m4: Improve the path resolution for xerces. * ../src/benchs/eps_removal/Makefile.am, * ../src/benchs/eps_removal/eps_removal-bench.cc, * ../src/benchs/generate_benchs.sh: Fix a missing file generation.