oap: add oap testsuite skeleton

Sponsored-by: On-Waves ehf
diff --git a/openbsc/tests/Makefile.am b/openbsc/tests/Makefile.am
index 773830b..1b557d4 100644
--- a/openbsc/tests/Makefile.am
+++ b/openbsc/tests/Makefile.am
@@ -1,4 +1,4 @@
-SUBDIRS = gsm0408 db channel mgcp gprs abis gbproxy trau subscr
+SUBDIRS = gsm0408 db channel mgcp gprs abis gbproxy trau subscr oap
 
 if BUILD_NAT
 SUBDIRS += bsc-nat bsc-nat-trie