Remove `proc` argument from LockCheckConflicts

This has been unused since commit 8563ccae2c.

Noted by Antonin Houska

src/backend/storage/lmgr/lock.c

@@ -906,7 +906,7 @@ LockAcquireExtended(const LOCKTAG *locktag,
 		status = STATUS_FOUND;
 	else
 		status = LockCheckConflicts(lockMethodTable, lockmode,
-									lock, proclock, MyProc);
+									lock, proclock);
 
 	if (status == STATUS_OK)
 	{
@@ -1256,8 +1256,7 @@ int
 LockCheckConflicts(LockMethod lockMethodTable,
 				   LOCKMODE lockmode,
 				   LOCK *lock,
-				   PROCLOCK *proclock,
-				   PGPROC *proc)
+				   PROCLOCK *proclock)
 {
 	int			numLockModes = lockMethodTable->numLockModes;
 	LOCKMASK	myLocks;

src/backend/storage/lmgr/proc.c

@@ -997,8 +997,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 					LockCheckConflicts(lockMethodTable,
 									   lockmode,
 									   lock,
-									   proclock,
-									   MyProc) == STATUS_OK)
+									   proclock) == STATUS_OK)
 				{
 					/* Skip the wait and just grant myself the lock. */
 					GrantLock(lock, proclock, lockmode);
@@ -1384,8 +1383,7 @@ ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock)
 			LockCheckConflicts(lockMethodTable,
 							   lockmode,
 							   lock,
-							   proc->waitProcLock,
-							   proc) == STATUS_OK)
+							   proc->waitProcLock) == STATUS_OK)
 		{
 			/* OK to waken */
 			GrantLock(lock, proc->waitProcLock, lockmode);

src/include/storage/lock.h

@@ -503,7 +503,7 @@ extern void AtPrepare_Locks(void);
 extern void PostPrepare_Locks(TransactionId xid);
 extern int LockCheckConflicts(LockMethod lockMethodTable,
 				   LOCKMODE lockmode,
-				   LOCK *lock, PROCLOCK *proclock, PGPROC *proc);
+				   LOCK *lock, PROCLOCK *proclock);
 extern void GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode);
 extern void GrantAwaitedLock(void);
 extern void RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode);