util: move CFReleaser from security/tpm

CFReleaser is used by both TPM backend and NetworkMonitor.

refs #3940

Change-Id: I39222bb4dec686d9338e6c4cb71108dd67f6cca1
diff --git a/src/security/tpm/back-end-osx.cpp b/src/security/tpm/back-end-osx.cpp
index 7f1aed1..53c2295 100644
--- a/src/security/tpm/back-end-osx.cpp
+++ b/src/security/tpm/back-end-osx.cpp
@@ -21,7 +21,6 @@
 
 #include "back-end-osx.hpp"
 #include "key-handle-osx.hpp"
-#include "helper-osx.hpp"
 #include "../transform/private-key.hpp"
 #include "tpm.hpp"
 
@@ -34,6 +33,8 @@
 namespace security {
 namespace tpm {
 
+using util::CFReleaser;
+
 class BackEndOsx::Impl
 {
 public: