Normalize includes relative to source root

For unit test cases it is cleaner to have include file paths relative to
source root (e.g. #include attn/attn_handler.hpp).

Signed-off-by: Ben Tyner <ben.tyner@ibm.com>
Change-Id: Id718e57e9ba8da4c2ff3bb11b1c7a61537da538a
diff --git a/attn/attn_main.cpp b/attn/attn_main.cpp
index bd3b5c4..0c3f250 100644
--- a/attn/attn_main.cpp
+++ b/attn/attn_main.cpp
@@ -1,4 +1,4 @@
-#include <../attn/attn_monitor.hpp>
+#include <attn/attn_monitor.hpp>
 
 namespace attn
 {