_DEPENDENCIES : looking to make it do more

[strnbrg]

It seems that automake's _DEPENDENCIES variable doesn't quite establish
a dependency in the full sense of the word, the way one might expect
from experience with make or gmake.

Say I'm building a program (foo.exe) that depends on a library
(somelib.so) that's built in another directory.  I've built somelib and
foo.  Now I touch somelibsrc.c, which somelib depends on.  If I'm in
foo's directory and I type "make", it tells me there's nothing to be
done.

Is there any way I can tell Makefile.am that, in such a case, I don't
consider foo to be current, i.e. that I'd like somelib.so to be rebuilt
(even though I'm typing "make" from foo's directory)?