Now can initial_placement in parallel placement

In 2014-06-10, I modified place_parallel.c as following:
1) change <= knum_net_pins to < knum_net_pins, due to VPR4.3 ADT;

2) modify compute_net_pin_index_value to VPR4.3 version, nowadays
it will never use VPR5.0.2 vesion;

3) modify find_to()(call by try_swap) in place_parallel.c to VPR4.3 version,
nowadays it will never use VPR5.0.2 version;

4) in try_place_use_multi_threads(), I new added g_pins_on_clb;