Fix NULL input behaviour of pg_stat_get_replication_slot().

pg_stat_get_replication_slot() accidentally was marked as non-strict, crashing
when called with NULL input. As it's already released, introduce an explicit
NULL check in 14, fix the catalog in HEAD.

Bumps catversion in HEAD.

Discussion: https://postgr.es/m/20220326212432.s5n2maw6kugnpyxw@alap3.anarazel.de
Backpatch: 14-, where replication slot stats were introduced

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202203241
+#define CATALOG_VERSION_NO	202203271
 
 #endif

src/include/catalog/pg_proc.dat

@@ -5370,7 +5370,7 @@
   proargnames => '{pid,status,receive_start_lsn,receive_start_tli,written_lsn,flushed_lsn,received_tli,last_msg_send_time,last_msg_receipt_time,latest_end_lsn,latest_end_time,slot_name,sender_host,sender_port,conninfo}',
   prosrc => 'pg_stat_get_wal_receiver' },
 { oid => '6169', descr => 'statistics: information about replication slot',
-  proname => 'pg_stat_get_replication_slot', proisstrict => 'f', provolatile => 's',
+  proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
   proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
   proargmodes => '{i,o,o,o,o,o,o,o,o,o,o}',

src/test/regress/expected/stats.out

@@ -255,4 +255,11 @@ SELECT pg_stat_get_tuples_hot_updated('brin_hot'::regclass::oid);
 
 DROP TABLE brin_hot;
 DROP FUNCTION wait_for_hot_stats();
+-- ensure that stats accessors handle NULL input correctly
+SELECT pg_stat_get_replication_slot(NULL);
+ pg_stat_get_replication_slot 
+------------------------------
+ 
+(1 row)
+
 -- End of Stats Test

src/test/regress/sql/stats.sql

@@ -229,4 +229,8 @@ DROP TABLE brin_hot;
 DROP FUNCTION wait_for_hot_stats();
 
 
+-- ensure that stats accessors handle NULL input correctly
+SELECT pg_stat_get_replication_slot(NULL);
+
+
 -- End of Stats Test