bin/45226: add option to make(1) to reverse/randomize sequences between .WAIT

[Taylor R Campbell <campbell+netbsd%mumble.net@localhost>]

>Number:         45226
>Category:       bin
>Synopsis:       add make(1) option to reverse/randomize sequences between .WAIT
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Mon Aug 08 16:35:00 +0000 2011
>Originator:     Taylor R Campbell <campbell+netbsd%mumble.net@localhost>
>Release:        NetBSD 5.99.55
>Organization:
>Environment:
System: NetBSD oberon.local 5.99.55 NetBSD 5.99.55 (RIAMONODEBUG) #1: Thu Aug 4 
03:23:52 UTC 2011 
root@oberon.local:/home/riastradh/netbsd/current/obj/sys/arch/i386/compile/RIAMONODEBUG
 i386
Architecture: i386
Machine: i386
>Description:

        Large source trees such as NetBSD have complex dependency
        structures which are often not correctly reflected in the
        makefiles, but in which mistakes do not manifest themselves
        except during unlucky builds with large numbers of parallel
        jobs.  I suspect that many obscure mistakes are simply omitted
        dependencies that happen to be implied by sequencing such as

                foo: bar baz

        where baz actually depends on bar too but someone forgot to say
        so.  Reversing, or perhaps randomly permuting, the implied
        sequences, might help to weed out some of these bugs.

>How-To-Repeat:

        Trawl the lists for instances of obscure parallel build
        failures.

>Fix:

        Yes, please!