build: Add a test directory

Add a test directory to host future unit tests.

Change-Id: I5072cb3055386f7b1718edc45241c723d9e63a54
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/src/Makefile.am b/src/Makefile.am
index 3fc5554..0dfe63b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -29,3 +29,5 @@
 		-d ${srcdir}/example \
 		-o ${builddir}/$@ \
 		generate-cpp
+
+SUBDIRS = . test