Makefile: remove harmful DEPENDENCIES
Defining %_DEPENDENCIES
means that the dependencies that
might be added to %_LIBADD
or %_LDADD
will not be accounted
correctly, whereas dependencies in in %_LIBADD
will automatically
be accounted into the %_DEPENDENCIES
if left unspecified.
Automake also allows EXTRA_%_DEPENDENCIES
to add new dependencies to the automake-generated ones.