Move out gtphub to its own subdir

Change-Id: I707d5e9b775179e732d281ce3d245de83d648eea
diff --git a/configure.ac b/configure.ac
index 1c3f03b..6672204 100644
--- a/configure.ac
+++ b/configure.ac
@@ -248,6 +248,7 @@
     src/Makefile
     src/gprs/Makefile
     src/gbproxy/Makefile
+    src/gtphub/Makefile
     tests/Makefile
     tests/atlocal
     tests/gprs/Makefile