[Patch, Darwin] update t-* and x-* fragments after switch to auto-deps.

[Tom Tromey]

>>>>> "Iain" == Iain Sandoe <iain@codesourcery.com> writes:

Joseph> Do you need these compilation rules at all?  Or could you change
Joseph> config.host to use paths such as config/host-darwin.o rather
Joseph> than just host-darwin.o, and so allow the generic rules to be
Joseph> used (my understanding was that the auto-deps patch series made
Joseph> lots of such changes to the locations of .o files in the build
Joseph> tree to avoid needing special compilation rules for particular
Joseph> files)?

Iain> I had a look at this, and it seems like a useful objective.  However,
Iain> unless I'm missing a step, [following the template of
Iain> config.gcc:out_file] it seem to require a fair amount of modification
Iain> (introduction of common-object placeholders etc. in the configury and
Iain> Makefile.in) - plus application and testing of this on multiple
Iain> targets.  Not something I can realistically volunteer to do in the
Iain> immediate future.

I think it can be done more simply using vpath.  (But I haven't tried
this.)  It seems to me though that the out_file stuff is overly manual
and perhaps predates the GNU make requirement.

Something like:

    vpath %.c $(dir $(tmake_file))
    vpath %.c $(dir $(xmake_file))

This would let us keep the .o file in ".".  Right now, adding a new
directory in which .o files may appear is a bit of a pain, because
configure.ac hard-codes the list of such directories.  (This could also
be moved into Makefile, it just seemed more complicated that way...)

Maybe it could also be done by writing a pattern rule that looks in
those directories; though this is more of a pain because tmake_file and
xmake_file can each list multiple files.

Tom