Reset front end trees before they make it into the middle end (PR middle-end/97172).

Reset front end trees before they make it into the middle end (PR middle-end/97172).

gcc/ChangeLog:

	PR middle-end/97172
	* attribs.c (attr_access::free_lang_data): Define new function.
	* attribs.h (attr_access::free_lang_data): Declare new function.

gcc/c/ChangeLog:

	PR middle-end/97172
	* c-decl.c (free_attr_access_data): New function.
	(c_parse_final_cleanups): Call free_attr_access_data.

gcc/testsuite/ChangeLog:

	PR middle-end/97172
	* gcc.dg/pr97172.c: New test.