Fix typo in proc.c
Author: Julien Rouhaud
Discussion:
@@ -851,7 +851,7 @@ ProcKill(int code, Datum arg)
/*
* Detach from any lock group of which we are a member. If the leader
- * exist before all other group members, it's PGPROC will remain allocated
+ * exist before all other group members, its PGPROC will remain allocated
* until the last group process exits; that process must return the
* leader's PGPROC to the appropriate list.
*/
