cat >> configure.ac << 'END'
AC_PROG_CC
-AM_PROG_CC_C_O
AC_PROG_CXX
AC_CONFIG_FILES([d1/Makefile d2/Makefile])
AC_OUTPUT
cat > d2/Makefile.am << 'END'
END
-: > compile
: > d2/z.c
$ACLOCAL
-$AUTOMAKE
+$AUTOMAKE -Wno-unsupported
grep '\$(CC) .*\.\./d2/z\.c' d1/Makefile.in