header: install test mock headers

IPMI Blob handlers will need to include these mocks when building
unit-tests.  Therefore, they must be installed.

Change-Id: I4c8ed0fa1a4a8912853c024206ef5e61f87707d8
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/test/ipmi_commit_unittest.cpp b/test/ipmi_commit_unittest.cpp
index 1cc47a4..34ff10d 100644
--- a/test/ipmi_commit_unittest.cpp
+++ b/test/ipmi_commit_unittest.cpp
@@ -1,6 +1,6 @@
 #include "ipmi.hpp"
-#include "manager_mock.hpp"
 
+#include <blobs-ipmid/test/manager_mock.hpp>
 #include <cstring>
 
 #include <gtest/gtest.h>