Listing both one after another leads to withXaw being false
if you pass "--with-Xaw3d --without-Xaw".
dnl | make results available in Makefile.am
AM_CONDITIONAL([withGTK], [test x"$with_GTK" = x"yes"])
-AM_CONDITIONAL([withXaw], [test x"$with_Xaw3d" = x"yes"])
-AM_CONDITIONAL([withXaw], [test x"$with_Xaw" = x"yes"])
+AM_CONDITIONAL([withXaw], [test x"$with_Xaw3d" = x"yes" || test x"$with_Xaw" = x"yes"])
AC_SUBST(FRONTEND_CFLAGS)