Add accept4 unit test to bionic.

Change-Id: I1cce5fb8dab16f03164fdd288f35a814d7c49c6a
diff --git a/tests/Android.mk b/tests/Android.mk
index 8dffa2f..a37ea4a 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -81,6 +81,7 @@
     system_properties_test.cpp \
     time_test.cpp \
     unistd_test.cpp \
+    accept4_test.cpp \
 
 libBionicStandardTests_cflags := \
     $(test_cflags) \