Harmonise test execution reporting across protocols

Report both the full command and the timeout value consistently across
various communication protocols, and always always output the report to
the log file, so that procedures do not have to be locally overridden to
extract this data where needed to reproduce an issue by hand.

	* baseboards/qemu.exp (qemu_load): Add execution reporting.
	* config/gdb-comm.exp (gdb_comm_load): Likewise.
	* config/gdb_stub.exp (gdb_stub_load): Likewise.
	* config/sim.exp (sim_load): Likewise.
	* config/unix.exp (unix_load): Report full command in addition
	to timeout value.