Fix panic return type

Signed-off-by: Marcos Lilljedahl <marcosnils@gmail.com>

entry.go

diff --git a/entry.go b/entry.go
index 8a522f0..001c4c7 100644
--- a/entry.go
+++ b/entry.go
@@ -100,7 +100,7 @@
 	// panic() to use in Entry#Panic(), we avoid the allocation by checking
 	// directly here.
 	if level <= PanicLevel {
-		panic(entry)
+		panic(&entry)
 	}
 }