build: enable valgrind

Enable valgrind to check memory usage.

Change-Id: Ib8d3affd895657864cdddade29a5871892840c5c
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/test/Makefile.am b/test/Makefile.am
index 0f0a18e..c8eee3f 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -1,3 +1,5 @@
+@VALGRIND_CHECK_RULES@
+
 AM_CPPFLAGS = \
 	-I$(top_srcdir)/ \
 	-I$(top_srcdir)/tools/ \