Also substitute abs_srcdir and abs_builddir, not alls autoconf versions do

that automatically.

[[Imported from SVN: r5845]]

m4/dune_all.m4

@@ -50,7 +50,9 @@ dnl do not use LT_INIT since we want to be compatible with libtool 1.5
 
   AC_SUBST([ACLOCAL_AMFLAGS], "$ACLOCAL_AMFLAGS")
 
+  AC_SUBST([abs_srcdir])
   AC_SUBST([abs_top_srcdir])
+  AC_SUBST([abs_builddir])
   AC_SUBST([abs_top_builddir])
   AC_SUBST(am_dir, $DUNE_COMMON_ROOT/am)
 ])