Add Poly1305 authenticator algorithm (RFC 7539)

Test vectors are included from RFC 7539.

Poly1305 is also added to the benchmark program.
diff --git a/tests/Makefile b/tests/Makefile
index 34a0a89..90b2028 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -82,6 +82,7 @@
 	test_suite_pkcs1_v21$(EXEXT)	test_suite_pkcs5$(EXEXT)	\
 	test_suite_pkparse$(EXEXT)	test_suite_pkwrite$(EXEXT)	\
 	test_suite_pk$(EXEXT)						\
+	test_suite_poly1305$(EXEXT)					\
 	test_suite_rsa$(EXEXT)		test_suite_shax$(EXEXT)		\
 	test_suite_ssl$(EXEXT)		test_suite_timing$(EXEXT)			\
 	test_suite_x509parse$(EXEXT)	test_suite_x509write$(EXEXT)	\
@@ -414,6 +415,10 @@
 	echo "  CC    $<"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) $<	$(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
 
+test_suite_poly1305$(EXEXT): test_suite_poly1305.c $(DEP)
+	echo "  CC    $<"
+	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) $<	$(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
+
 test_suite_rsa$(EXEXT): test_suite_rsa.c $(DEP)
 	echo "  CC    $<"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) $<	$(LOCAL_LDFLAGS) $(LDFLAGS) -o $@