build: enable valgrind

Enable valgrind to check memory usage.

Change-Id: If6b91a6239ba9b1cb182fd4ecf4572fec13a872f
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/test/Makefile.am b/test/Makefile.am
index 0468348..a4be5a7 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -1,3 +1,5 @@
+@VALGRIND_CHECK_RULES@
+
 AM_CPPFLAGS = \
 	-I$(top_srcdir)/ \
 	$(GTEST_CFLAGS) \