Bug#4073: make pattern rules delete intermediate files

[Ian Jackson <ijackson@chiark.chu.cam.ac.uk>]

I've since found the documentation where it explains where this
happens.

However:

(a) It doesn't say that it doesn't remove the intermediate targets of
suffix rules.

(b) The documented way to turn it off, using .PRECIOUS, has other
undesirable side-effects - namely, it prevents make from removing the
file when interrupted, so that the timestamp may be wrong for the next
build.

(c) I think that the feature is of doubtful value anyway, especially
when the final target has dependencies other than the intermediate
target.

(d) There is no general way to turn the feature off, except perhaps by
saying `.PRECIOUS: %' - see (b).

My apologies for missing the documentation for this the first time
round, but I still think there are issues to be resolved here.

Ian.