Fix silly initializations (cosmetic only).

Initializing a pointer to "false" isn't per project style, and reportedly some compilers warn about it (though I've not seen any such warnings in the buildfarm). Seems to have come in with commit ff11e7f, so back-patch to v12 where that was added. Didier Gautheron Discussion: https://postgr.es/m/CAJRYxu+XQuM0qnSqt1Ujztu6fBPzMMAT3VEn6W32rgKG6A2Fsw@mail.gmail.com

Author: tglsfdc

src/backend/commands/trigger.c

@@ -2533,7 +2533,7 @@ ExecBRInsertTriggers(EState *estate, ResultRelInfo *relinfo,
  TupleTableSlot *slot)
 {
 TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
-HeapTuplenewtuple = false;
+HeapTuplenewtuple = NULL;
 boolshould_free;
 TriggerData LocTriggerData;
 inti;
@@ -3178,7 +3178,7 @@ ExecIRUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
 {
 TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
 TupleTableSlot *oldslot = ExecGetTriggerOldSlot(estate, relinfo);
-HeapTuplenewtuple = false;
+HeapTuplenewtuple = NULL;
 boolshould_free;
 TriggerData LocTriggerData;
 inti;