pkg/56924: Many packages ignore package specific MAKE_JOBS overrides

[stix%stix.id.au@localhost]

>Number:         56924
>Category:       pkg
>Synopsis:       Many packages ignore package specific MAKE_JOBS overrides
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jul 14 07:20:00 +0000 2022
>Originator:     Paul Ripke
>Release:        NetBSD 9.2
>Organization:
Paul Ripke
"Great minds discuss ideas, average minds discuss events, small minds
 discuss people."
-- Disputed: Often attributed to Eleanor Roosevelt. 1948.
>Environment:
System: NetBSD slave 9.2 NetBSD 9.2 (SLAVE) #9: Sat May 15 17:19:33 AEST 2021 stix@slave:/home/netbsd/netbsd-9/obj.amd64/home/netbsd/netbsd-9/src/sys/arch/amd64/compile/SLAVE amd64
Architecture: x86_64
Machine: amd64
pkgsrc-2022Q2
>Description:
See thread:
http://mail-index.netbsd.org/tech-pkg/2020/11/04/msg024021.html

Many packages reference MAKE_JOBS in their makefiles, eg:

ksh$ grep MAKE_JOBS x11/qt5-qtwebengine/Makefile
MAKE_ENV+=      NINJAJOBS="-j ${MAKE_JOBS:U1}"

However, if setting a manual override in mk.conf:

MAKE_JOBS.x11/qt5-qtwebengine=4

the override is ignored, and the default used. Substituting _MAKE_JOBS_N
for MAKE_JOBS works, and is used in many other packages, eg:

ksh$ grep _MAKE_JOBS_N devel/cmake/Makefile
CONFIGURE_ARGS+=        --parallel=${_MAKE_JOBS_N:U1}

but this (I believe) is supposed to be an internal variable.

>How-To-Repeat:
Build x11/qt5-qtwebengine and watch swap fill up?
>Fix:
All packages should use _MAKE_JOBS_N or a new appropriate variable.

See possible patch referenced in the mail thread above:
https://gist.github.com/jperkin/b390f0d922e5c22430ae7f2d8131a158