crypto: add import comments.

Change-Id: I33240faf1b8620d0cd600de661928d8e422ebdbc
Reviewed-on: https://go-review.googlesource.com/1235
Reviewed-by: Andrew Gerrand <adg@golang.org>
diff --git a/bcrypt/bcrypt.go b/bcrypt/bcrypt.go
index b8e18d7..f8b807f 100644
--- a/bcrypt/bcrypt.go
+++ b/bcrypt/bcrypt.go
@@ -4,7 +4,7 @@
 
 // Package bcrypt implements Provos and Mazières's bcrypt adaptive hashing
 // algorithm. See http://www.usenix.org/event/usenix99/provos/provos.pdf
-package bcrypt
+package bcrypt // import "golang.org/x/crypto/bcrypt"
 
 // The code is a port of Provos and Mazières's C implementation.
 import (