MINOR: threads: make use of thread_mask() to simplify some thread calculations

By doing so it's visible that some fd_insert() calls were relying on
MAX_THREADS while all_threads_mask should have been more suitable.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 917fe0c..3e8a7f5 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -2287,8 +2287,8 @@
 
 			/* detect and address thread affinity inconsistencies */
 			nbproc = my_ffsl(proc_mask(bind_conf->bind_proc)) - 1;
-			mask = bind_conf->bind_thread[nbproc];
-			if (mask && !(mask & all_threads_mask)) {
+			mask = thread_mask(bind_conf->bind_thread[nbproc]);
+			if (!(mask & all_threads_mask)) {
 				unsigned long new_mask = 0;
 
 				while (mask) {
diff --git a/src/proto_sockpair.c b/src/proto_sockpair.c
index 068b24f..9105dd2 100644
--- a/src/proto_sockpair.c
+++ b/src/proto_sockpair.c
@@ -153,8 +153,7 @@
 	listener->state = LI_LISTEN;
 
 	fd_insert(fd, listener, listener->proto->accept,
-		  listener->bind_conf->bind_thread[relative_pid-1] ?
-		  listener->bind_conf->bind_thread[relative_pid-1] : MAX_THREADS_MASK);
+	          thread_mask(listener->bind_conf->bind_thread[relative_pid-1]));
 
 	return err;
 
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index 52a4691..e4b8f63 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -1076,8 +1076,7 @@
 	listener->state = LI_LISTEN;
 
 	fd_insert(fd, listener, listener->proto->accept,
-		  listener->bind_conf->bind_thread[relative_pid-1] ?
-		  listener->bind_conf->bind_thread[relative_pid-1] : MAX_THREADS_MASK);
+	          thread_mask(listener->bind_conf->bind_thread[relative_pid-1]));
 
  tcp_return:
 	if (msg && errlen) {
diff --git a/src/proto_uxst.c b/src/proto_uxst.c
index 965b7cb..7fc145b 100644
--- a/src/proto_uxst.c
+++ b/src/proto_uxst.c
@@ -340,8 +340,7 @@
 	listener->state = LI_LISTEN;
 
 	fd_insert(fd, listener, listener->proto->accept,
-		  listener->bind_conf->bind_thread[relative_pid-1] ?
-		  listener->bind_conf->bind_thread[relative_pid-1] : MAX_THREADS_MASK);
+	          thread_mask(listener->bind_conf->bind_thread[relative_pid-1]));
 
 	return err;