the root of a product to reduce its number of successors.
* src/tgba/Makefile.am (libtgba_la_SOURCES): Add tgba.cc.
* src/tgba/tgba.hh (tgba::succ_iter): Add the global_state and
global_automaton arguments.
(tgba::support_conditions, tgba::support_variables,
tgba::compute_support_conditions, tgba::compute_support_variables):
New functions.
(tgba::last_support_conditions_input_,
tgba::last_support_conditions_output_,
tgba::last_support_variables_input_,
tgba::last_support_variables_output_): New attributes.
* src/tgba/tgbabddconcrete.cc (tgba_bdd_concrete::succ_iter):
Handle the two new arguments.
(tgba_bdd_concrete::compute_support_conditions,
tgba_bdd_concrete::compute_support_variables): Implement them.
* src/tgba/tgbabddconcrete.hh: Adjust.
* src/tgba/tgbaexplicit.cc (tgba_explicit::succ_iter):	Ignore
the two new arguments.
(tgba_explicit::compute_support_conditions,
tgba_explicit::compute_support_variables): Implement them.
* src/tgba/tgbaexplicit.hh: Adjust.
* src/tgba/tgbaproduct.cc (tgba_product::succ_iter): Handle the
two new arguments.
(tgba_product::compute_support_conditions,
tgba_product::compute_support_variables): Implement them.
* src/tgba/tgbaproduct.hh: Adjust.
* iface/gspn/gspn.cc (tgba_gspn_private_::last_state_cond_input,
tgba_gspn_private_::last_state_cond_output,
(tgba_gspn_private_::tgba_gspn_private_): Set last_state_cond_input.
(tgba_gspn_private_::~tgba_gspn_private_): Delete
last_state_cond_input.
(tgba_gspn_private_::state_conds): New function, eved out
from tgba_gspn::succ_iter.
(tgba_gspn::succ_iter): Use it.  Use the two new arguments.
(tgba_gspn::compute_support_conditions,
tgba_gspn::compute_support_variables): New functions.
* iface/gspn/gspn.hh: Adjust.