PR gdb/13431:

	PR gdb/13431:
	* jit.c (struct jit_inferior_data): Rewrite.
	(struct jit_objfile_data): New.
	(get_jit_objfile_data): New function.
	(add_objfile_entry): Update.
	(jit_read_descriptor): Return int.  Replace descriptor_addr
	argument with inf_data.  Update.  Don't call error.
	(jit_breakpoint_re_set_internal): Reorder logic.  Update.  Look up
	descriptor here.
	(jit_inferior_init): Don't look up descriptor.  Don't call error.
	(jit_reset_inferior_data_and_breakpoints)
	(jit_inferior_created_observer): Remove.
	(jit_inferior_exit_hook): Update.
	(jit_executable_changed_observer): Remove.
	(jit_event_handler): Update.
	(free_objfile_data): Reset inferior data if needed.
	(_initialize_jit): Update.
gdb/testsuite
	* gdb.base/jit-simple.exp: New file.
	* gdb.base/jit-simple.c: New file.