add pthread_mutex_protects_3() -- semantic helper

This will be our helper for making modifications of code.
It hints as to what data items a mutex protects. It
does not hing at run time code for production and in-tree.

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>

main.c

diff --git a/main.c b/main.c
index 5f589cc..2fe9a0f 100644
--- a/main.c
+++ b/main.c
@@ -119,6 +119,8 @@
 	printf(" ]\n");
 }
 
+#define pthread_mutex_protects_3(mutex, var1, var2, var3)
+
 int main(int argc, char *argv[])
 {
 	pthread_t threads[NUM_THREADS];
@@ -142,6 +144,10 @@
 	show_party(party);
 
 	pthread_mutex_init(&party->mutex, NULL);
+	pthread_mutex_protects_3(&party->mutex,
+				 party->food,
+				 party->trash,
+				 party->tid_status);
 
 	pthread_attr_init(&attr);
 	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);