configure.in (toplevel_srcdir, auxdir): Set.

* configure.in (toplevel_srcdir, auxdir): Set.
* acinclude.m4 (glibcpp_basedir): Set based on auxdir.
* aclocal.m4, configure, Makefile.in: Rebuilt.
* libio/Makefile.in, math/Makefile.in, src/Makefile.in: Likewise.
* libsupc++-v3/Makefile.am (INCLUDES): Use toplevel_srcdir.
* libsupc++-v3/Makefile.in: Rebuilt.
* libsupc++-v3/configure.in, libsupc++-v3/configure: Removed.
* libsupc++-v3/aclocal.m4, libsupc++-v3/config.h.in: Likewise.

From-SVN: r39395