rename oap.h to oap_client.h

Related: OS#1592
Change-Id: I05bd65ff81b0f70f68217b2e0a9466e160bdbdec
diff --git a/openbsc/include/openbsc/gsup_client.h b/openbsc/include/openbsc/gsup_client.h
index d21a54d..a113225 100644
--- a/openbsc/include/openbsc/gsup_client.h
+++ b/openbsc/include/openbsc/gsup_client.h
@@ -23,7 +23,7 @@
 
 #include <osmocom/core/timer.h>
 
-#include <openbsc/oap.h>
+#include <openbsc/oap_client.h>
 
 #define GSUP_CLIENT_RECONNECT_INTERVAL 10
 #define GSUP_CLIENT_PING_INTERVAL 20