toyvm.c: use correct path in debuginfo

toyvm.c: use correct path in debuginfo

gcc/jit/ChangeLog:
	* docs/examples/tut04-toyvm/toyvm.c (toyvm_function_compile): Move
	logic for determine "funcname" to new function...
	(get_function_name): ...here, adding logic to skip any leading
	path from the filename.
	(toyvm_function_parse): Use the filename for fn_filename, rather
	than "name", so that the debugger can locate the source .toy
	file.
	(toyvm_function_parse): Don't fclose a NULL FILE *.

From-SVN: r218540