SUBST suffix removal (was: make variable expansion oddity)

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

EF> Is there a variant of the SUBST framework that converts foo.in to foo 
EF> instead of working on foo?

RI> No, there isn't. Currently, you would have to emulate in your own code
RI> what subst.mk does.

RI> Given that it were implemented, how would you like to use this feature,
RI> using the following example?

SUBST_INSUFFIX.in=	.in

(plus SUBST_OUTSUFFIX and a revised logic for the case that either one is 
present so you don't need the temp file.)