Move helper scripts to build-aux.
* compile, config.guess, config.rpath, config.sub, depcomp, ltmain.sh * doc/mdate-sh, doc/texinfo.tex, install-sh, missing: Move to build-aux/. * Makefile.am (EXTRA_DIST): Remove config.rpath - it is implicitly distributed. * configure.ac (AC_CONFIG_AUX_DIR): New. (AM_SILENT_RULES): New.