BUILD: makefile: Update feature flags for NetBSD

This updates the feature flags for NetBSD.

NetBSD 8 adds support for accept4().

Enable getaddrinfo().
diff --git a/Makefile b/Makefile
index ecb034d..db9bbe7 100644
--- a/Makefile
+++ b/Makefile
@@ -393,10 +393,11 @@
     USE_GETADDRINFO)
 endif
 
-# NetBSD
+# NetBSD 8 and above
 ifeq ($(TARGET),netbsd)
   set_target_defaults = $(call default_opts, \
-    USE_POLL USE_TPROXY USE_KQUEUE)
+    USE_POLL USE_TPROXY USE_THREAD USE_KQUEUE USE_ACCEPT4 USE_CLOSEFROM   \
+    USE_GETADDRINFO)
 endif
 
 # AIX 5.1 only