[Libvir] moving "aux" files into a subdir

I noticed that gnulib-tool had deposited a file named link-warning.h into the top-level directory. How odd, I thought. This doesn't affect other projects because most of them define what autoconf calls the "AUX" directory, with a line like this in configure.in or configure.ac: AC_CONFIG_AUX_DIR(build-aux) If you don't define that, it defaults to the top level directory, and that's where files pulled in by gettextize like these are deposited: config.guess compile libtool ltconfig ltmain.sh config.sub config.rpath mkinstalldirs Rather than committing link-warning.h in the top-level, I propose to add the above AC_CONFIG_AUX_DIR line. That change should be transparent to all the other tools, and would let me commit link-warning.h in the build-aux subdir, instead of in the top-level dir. Any objection?