strsignal: Move AC_LIBOBJ invocations to module description. * m4/strsignal.m4 (gl_FUNC_STRSIGNAL): Set HAVE_STRSIGNAL. Move AC_LIBOBJ and gl_PREREQ_STRSIGNAL invocations from here... * modules/strsignal (configure.ac): ... to here. (Depends-on): Update conditions.