Add command to print the function names from recorded instructions.

Add command to print the function names from recorded instructions.

This command provides a quick high-level overview over the recorded execution
log at function granularity without having to reverse-step.

gdb/
	* target.c (target_call_history, target_call_history_from,
	target_call_history_range): New.
	* target.h (target_ops) <to_call_history, to_call_history_from,
	to_call_history_range>: New fields.
	(target_call_history, target_call_history_from,
	target_call_history_range): New declaration.
	* record.c (get_call_history_modifiers, cmd_record_call_history,
	record_call_history_size): New.
	(_initialize_record): Add the "record function-call-history" command.
	Add "set/show record function-call-history-size" commands.
	* record.h (record_print_flag): New.