Embedded: disable stats test

As of 67bdd80a96bdfc49d1aadbd32cca2b53f123d180 the stats.c is
effectively disable so we should disable the corresponding tests as
well.

Change-Id: I42ff7a6619c0a5926fdc2ec779cf04689c567e15
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 877a302..e199ccc 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -17,7 +17,7 @@
 		 write_queue/wqueue_test socket/socket_test		\
 		 coding/coding_test conv/conv_gsm0503_test		\
 		 abis/abis_test endian/endian_test sercomm/sercomm_test	\
-		 stats/stats_test prbs/prbs_test gsm23003/gsm23003_test \
+		 prbs/prbs_test gsm23003/gsm23003_test 			\
 		 codec/codec_ecu_fr_test
 
 if ENABLE_MSGFILE
@@ -40,6 +40,10 @@
 check_PROGRAMS += ctrl/ctrl_test fsm/fsm_test
 endif
 
+if ENABLE_STATS_TEST
+check_PROGRAMS += stats/stats_test
+endif
+
 if ENABLE_GB
 check_PROGRAMS += gb/bssgp_fc_test gb/gprs_bssgp_test gb/gprs_ns_test fr/fr_test
 endif