test: Add tools to search path

Add tools to makefile's header search path.

Change-Id: Ibd9d560b02c31aa3a25b5ecf52cb6671933051e2
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/test/Makefile.am b/test/Makefile.am
index 8e7dada..aac24a1 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -1,4 +1,5 @@
 AM_CPPFLAGS = -I$(top_srcdir)/ \
+	-I$(top_srcdir)/tools/ \
 	$(GTEST_CFLAGS) \
 	$(GMOCK_CFLAGS)
 AM_CXXFLAGS = \