xfsrestore: untangle inventory unpacking logic

stobj_unpack_sessinfo returns bool_t, fix logic in pi_addfile so errors
can be properly reported.

Signed-off-by: Donald Douwsma <ddouwsma@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
diff --git a/restore/content.c b/restore/content.c
index b19bb90..8bb5fa4 100644
--- a/restore/content.c
+++ b/restore/content.c
@@ -5450,17 +5450,14 @@
 			 * desc.
 			 */
 			sessp = 0;
-			if (!buflen) {
-				ok = BOOL_FALSE;
-			} else {
-			    /* extract the session information from the buffer */
-			    if (stobj_unpack_sessinfo(bufp, buflen, &sessinfo)<0) {
-				ok = BOOL_FALSE;
-			    } else {
+			ok = BOOL_FALSE;
+			/* extract the session information from the buffer */
+			if (buflen &&
+			    stobj_unpack_sessinfo(bufp, buflen, &sessinfo)) {
 				stobj_convert_sessinfo(&sessp, &sessinfo);
 				ok = BOOL_TRUE;
-			    }
 			}
+
 			if (!ok || !sessp) {
 				mlog(MLOG_DEBUG | MLOG_WARNING | MLOG_MEDIA, _(
 				      "on-media session "