Avoid some overflow cases:

	Avoid some overflow cases:
	* basic_blocks.h (bb_min_calls): Change to unsigned long.
	* call_graph.h (cg_tally): Change count parameter to unsigned
	long.
	* cg_arcs.h (Arc): Change count field to unsigned long.
	(arc_add): Change count parameter to unsigned long.
	* source.h (Source_File): Change ncalls field to unsigned long.
	* symtab.h (Sym): Change fields ncalls, bb_calls, and
	cg.self_calls to unsigned long.
	* Many files: Update accordingly.