Print -de error information when running multiple jobs

Problem and patch description from https://reviews.freebsd.org/D29647:

When running `make -de` (without any -j flag) bmake prints which command
failed. However, when using the -j flag the -de flag is ignored. This can
make it rather difficult to determine which command failed in an very
parallel build (especially when combined with the -s flag to avoid
ridiculously large logfiles). For single-threaded builds we can combine
-s with -de to get the failed command but this does not work with -jN
(even with -j1). This patch prints the failed shell script with -de in the
multiple jobs mode as well.

From Alexander Richardson @ FreeBSD

usr.bin/make/job.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: job.c,v 1.429 2021/04/16 16:49:27 rillig Exp $	*/
+/*	$NetBSD: job.c,v 1.430 2021/04/27 15:21:42 christos Exp $	*/
 
 /*
  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
@@ -142,7 +142,7 @@
 #include "trace.h"
 
 /*	"@(#)job.c	8.2 (Berkeley) 3/19/94"	*/
-MAKE_RCSID("$NetBSD: job.c,v 1.429 2021/04/16 16:49:27 rillig Exp $");
+MAKE_RCSID("$NetBSD: job.c,v 1.430 2021/04/27 15:21:42 christos Exp $");
 
 /*
  * A shell defines how the commands are run.  All commands for a target are
@@ -1060,6 +1060,21 @@ JobClosePipes(Job *job)
 	job->inPipe = -1;
 }
 
+static void
+DebugFailedJob(const Job *job)
+{
+	const ListNode *l;
+
+	if (!DEBUG(ERROR))
+		return;
+
+	debug_printf("\n*** Failed target:  %s\n*** Failed commands:\n",
+	    job->node->name);
+	for (l = job->node->commands.first; l != NULL; l = l->next) {
+		debug_printf("\t%s\n", (const char *)l->datum);
+	}
+}
+
 static void
 JobFinishDoneExitedError(Job *job, int *inout_status)
 {
@@ -1071,6 +1086,7 @@ JobFinishDoneExitedError(Job *job, int *inout_status)
 	}
 #endif
 	if (!shouldDieQuietly(job->node, -1)) {
+		DebugFailedJob(job);
 		(void)printf("*** [%s] Error code %d%s\n",
 		    job->node->name, WEXITSTATUS(*inout_status),
 		    job->ignerr ? " (ignored)" : "");
@@ -1103,6 +1119,7 @@ static void
 JobFinishDoneSignaled(Job *job, int status)
 {
 	SwitchOutputTo(job->node);
+	DebugFailedJob(job);
 	(void)printf("*** [%s] Signal %d\n", job->node->name, WTERMSIG(status));
 	if (deleteOnError)
 		JobDeleteTarget(job->node);