libbpf: deprecate bpf_object__open_xattr() API

Deprecate bpf_object__open_xattr() in favor of
bpf_object__open_mem() instead.

Signed-off-by: Christy Lee <christylee@fb.com>

Author: christycylee

tools/lib/bpf/libbpf.c

@@ -9443,7 +9443,7 @@ static int bpf_prog_load_xattr2(const struct bpf_prog_load_attr *attr,
 	open_attr.file = attr->file;
 	open_attr.prog_type = attr->prog_type;
 
-	obj = bpf_object__open_xattr(&open_attr);
+	obj = libbpf_ptr(__bpf_object__open_xattr(&open_attr, 0));
 	err = libbpf_get_error(obj);
 	if (err)
 		return libbpf_err(-ENOENT);

tools/lib/bpf/libbpf.h

@@ -185,6 +185,7 @@ LIBBPF_DEPRECATED_SINCE(0, 8, "use bpf_object__open_mem() instead")
 LIBBPF_API struct bpf_object *
 bpf_object__open_buffer(const void *obj_buf, size_t obj_buf_sz,
 			const char *name);
+LIBBPF_DEPRECATED_SINCE(0, 8, "use bpf_object__open_mem() instead")
 LIBBPF_API struct bpf_object *
 bpf_object__open_xattr(struct bpf_object_open_attr *attr);