Rename consumerd32/64_path options to _bin

The _path suffix was confusing as to whether it would include the
filename at the end or not. In fact it should (to allow greater
flexibility in moving/renaming the consumerd executable).

Rename all configure options, env vars and substition variables to
consumerd32/64_bin instead, and expect the user to pass a complete
basename + filename to those.

Signed-off-by: Alexandre Montplaisir <alexandre.montplaisir@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>