Revert "Add key management system" (978f869b99) & later commits

The patch needs test cases, reorganization, and cfbot testing.
Technically reverts commits 5c31afc49d..e35b2bad1a (exclusive/inclusive)
and 08db7c63f3..ccbe34139b.

Reported-by: Tom Lane, Michael Paquier

Discussion: https://postgr.es/m/E1ktAAG-0002V2-VB@gemulon.postgresql.org

src/backend/storage/ipc/ipci.c

@@ -23,7 +23,6 @@
 #include "access/syncscan.h"
 #include "access/twophase.h"
 #include "commands/async.h"
-#include "crypto/kmgr.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "postmaster/autovacuum.h"
@@ -150,7 +149,6 @@ CreateSharedMemoryAndSemaphores(void)
 		size = add_size(size, BTreeShmemSize());
 		size = add_size(size, SyncScanShmemSize());
 		size = add_size(size, AsyncShmemSize());
-		size = add_size(size, KmgrShmemSize());
 #ifdef EXEC_BACKEND
 		size = add_size(size, ShmemBackendArraySize());
 #endif
@@ -269,7 +267,6 @@ CreateSharedMemoryAndSemaphores(void)
 	BTreeShmemInit();
 	SyncScanShmemInit();
 	AsyncShmemInit();
-	KmgrShmemInit();
 
 #ifdef EXEC_BACKEND
 

src/backend/storage/lmgr/lwlocknames.txt

@@ -53,4 +53,3 @@ XactTruncationLock					44
 # 45 was XactTruncationLock until removal of BackendRandomLock
 WrapLimitsVacuumLock				46
 NotifyQueueTailLock					47
-KmgrFileLock					48