Modified util.h/c to compatible with VPR5.0.2

I will portable VPR5_ParaPlace to VPR4.3, first I new added
some functions in VPR5_ParaPlace util.h/c, where wasn't in
VPR4.3 util.h/c. And modified the my_fopen().
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Due to I needn't place_parallel.h/c temporarily, so I deleted
it. And modieed member variable: occ in grid_tile_t(clb_t) and rr_node_t
to m_usage.
Update perform_timing_analyze() in place.c

I changed the judge condition in perform_timing_analyze() outside.
rain_main_placement() and run_low_temperature_placement() call this
function.