Some bugs spotted by coverity (#399)

Author: chrissie-c

include/tlist.h

@@ -191,7 +191,7 @@ static inline void timerlist_expire(struct timerlist *timerlist)
 	uint64_t current_time;
 
 	current_monotonic_time = qb_util_nano_current_get();
-	current_time_from_epoch = current_time = qb_util_nano_from_epoch_get();
+	current_time_from_epoch = qb_util_nano_from_epoch_get();
 
 	qb_list_for_each_safe(pos, next, &timerlist->timer_head) {
 

lib/ringbuffer.c

@@ -266,13 +266,13 @@ qb_rb_open_2(const char *name, size_t size, uint32_t flags,
 	if (fd_hdr >= 0) {
 		close(fd_hdr);
 	}
-	if (rb && (flags & QB_RB_FLAG_CREATE)) {
+	if (rb && (rb->shared_hdr != MAP_FAILED) && (flags & QB_RB_FLAG_CREATE)) {
 		unlink(rb->shared_hdr->hdr_path);
 		if (rb->notifier.destroy_fn) {
 			(void)rb->notifier.destroy_fn(rb->notifier.instance);
 		}
 	}
-	if (rb && (rb->shared_hdr != MAP_FAILED && rb->shared_hdr != NULL)) {
+	if (rb && (rb->shared_hdr != MAP_FAILED)) {
 		munmap(rb->shared_hdr, sizeof(struct qb_ringbuffer_shared_s));
 	}
 	free(rb);