I've read into more details your proposal, and it looks very good,
much more robust than the current approach in Automake IIRC.
I'm OK with integrating this with minor changes into Autoconf, but as
Automake 1.5 will already provide something similar (and it will not
require 2.51+ yet, 1.6 will) we should be sure to have the same
interface.
I.e., I propose that 1.5 integrates your proposal with AM_, and 2.51
with AC_, and AM_ AU defined to AC_.
BTW, does Automake *use* that feature? If not, then it should not
provide this macro IMHO. It should stop distributing macros, that's
Autoconf job, not Automake's.
