build: Makefile.am corrections (separate Makefile.am for tests)

Change-Id: I69f442d5b7dee7fd7c20d10bd4229e692ee1193d
diff --git a/configure.ac b/configure.ac
index 485a6ce..f04b30b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -159,5 +159,6 @@
 DX_INIT_DOXYGEN([$PACKAGE_NAME],[Doxyfile])
 
 AC_CONFIG_FILES([Makefile
-                 include/Makefile])
+                 include/Makefile
+                 tests/Makefile])
 AC_OUTPUT