ndn-cxx: Update to version 0.5.1

Change-Id: Ia5bd34f1ffe11ee5ef90ccefe0abb4224f217841
diff --git a/ndn-cxx/Makefile b/ndn-cxx/Makefile
index cdad606..d82a469 100644
--- a/ndn-cxx/Makefile
+++ b/ndn-cxx/Makefile
@@ -2,15 +2,15 @@
 GIT_URL=https://github.com/named-data/ndn-cxx.git
 
 # Tag name or commit hash for checkout
-GIT_VERSION=0669061ae857536d0f9538c29fabfb8212c597c1
+GIT_VERSION=ndn-cxx-0.5.1
 
 # Package name
 NAME=ndn-cxx
 
 # Package version
-VERSION=0.5.0-27-g0669061a
+VERSION=0.5.1
 
 # PPA version
-PPA_VERSION=1
+PPA_VERSION=4
 
 include ../packaging.mk