remote-sim.c: Add casts

remote-sim.c: Add casts

Mostly some casts from "generic arg" void* to the actual type.

There are two (enum gdb_signal) casts.  I tried to see if it would have
been better to change the type of sigrc, but it has a double role, as an
enum and as an integer, so I left it as is.

gdb/ChangeLog:

	* remote-sim.c (check_for_duplicate_sim_descriptor): Add casts.
	(get_sim_inferior_data): Likewise.
	(sim_inferior_data_cleanup): Likewise.
	(gdbsim_close_inferior): Likewise.
	(gdbsim_resume_inferior): Likewise.
	(gdbsim_wait): Likewise.
	(simulator_command): Likewise.
	(sim_command_completer): Likewise.