instrumentation: Drop INSTR_TIME_SET_CURRENT_LAZY macro

This macro had exactly one user in InstrStartNode, and the caller can
instead use INSTR_TIME_IS_ZERO / INSTR_TIME_SET_CURRENT directly.

This supports a future change that intends to modify the time source being
used in the InstrStartNode case.

Author: Lukas Fittl <lukas@fittl.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAP53Pkx1bK1FB71_nBqYmzvSSXnp_MbE0ZDnU+baPJF6Ud2WDA@mail.gmail.com

src/backend/executor/instrument.c

@@ -67,9 +67,13 @@ InstrInit(Instrumentation *instr, int instrument_options)
 void
 InstrStartNode(Instrumentation *instr)
 {
-	if (instr->need_timer &&
-		!INSTR_TIME_SET_CURRENT_LAZY(instr->starttime))
-		elog(ERROR, "InstrStartNode called twice in a row");
+	if (instr->need_timer)
+	{
+		if (!INSTR_TIME_IS_ZERO(instr->starttime))
+			elog(ERROR, "InstrStartNode called twice in a row");
+		else
+			INSTR_TIME_SET_CURRENT(instr->starttime);
+	}
 
 	/* save buffer usage totals at node entry, if needed */
 	if (instr->need_bufusage)

src/include/portability/instr_time.h

@@ -19,8 +19,6 @@
  *
  * INSTR_TIME_SET_CURRENT(t)		set t to current time
  *
- * INSTR_TIME_SET_CURRENT_LAZY(t)	set t to current time if t is zero,
- *									evaluates to whether t changed
  *
  * INSTR_TIME_ADD(x, y)				x += y
  *
@@ -170,12 +168,8 @@ GetTimerFrequency(void)
 
 #define INSTR_TIME_IS_ZERO(t)	((t).ticks == 0)
 
-
 #define INSTR_TIME_SET_ZERO(t)	((t).ticks = 0)
 
-#define INSTR_TIME_SET_CURRENT_LAZY(t) \
-	(INSTR_TIME_IS_ZERO(t) ? INSTR_TIME_SET_CURRENT(t), true : false)
-
 
 #define INSTR_TIME_ADD(x,y) \
 	((x).ticks += (y).ticks)