PR sanitizer/81981
	* gimple-fold.c (gimple_fold_call): Optimize away useless UBSAN_PTR
	and UBSAN_BOUNDS internal calls.  Clean up IFN_UBSAN_OBJECT_SIZE
	handling.  Use replace_call_with_value with NULL instead of
	gsi_replace, unlink_stmt_vdef and release_defs.

	* gcc.dg/ubsan/pr81981.c: New test.

From-SVN: r251641