firefox and MAKE_JOBS=1

[Greg Troxel <gdt%lexort.com@localhost>]

I have a config file with

MAKE_JOBS?=	1

that sometimes I change to 2.   Yes, I know that setting MAKE_JOBS to 1
is not useful vs not setting it, but IMHO it is not wrong.

I remember a while ago that firefox and some other rust things would
have problems in this case because of some double use of -j1 or
something like that, and also that this was fixed.

I just tried to build www/firefox (my rust-type is bin) on
netbsd-9/amd64 and got the cargo-unhappy-j message:

  gmake[1]: Entering directory '/tmp/work/www/firefox/work/build'
  /usr/pkg/bin/gmake recurse_compile
  gmake[2]: Entering directory '/tmp/work/www/firefox/work/build'
  gmake[3]: Entering directory '/tmp/work/www/firefox/work/build/toolkit/library/rust'
  toolkit/library/rust/force-cargo-library-build
  /usr/pkg/bin/cargo rustc  --release --frozen --manifest-path /tmp/work/www/firefox/work/firefox-112.0.1/toolkit/library/rust/Cargo.toml -j1 -j1   --lib --target=x86_64-unknown-netbsd --features 'gkrust-shared/moz_places gkrust-shared/webrtc gkrust-shared/glean_with_gecko gkrust-shared/glean_disable_upload gkrust-shared/glean_million_queue' --  -Clto=thin
  error: the argument '--jobs <N>' cannot be used multiple times

  Usage: cargo rustc [OPTIONS] [args]...

  For more information, try '--help'.
  gmake[3]: *** [/tmp/work/www/firefox/work/firefox-112.0.1/config/makefiles/rust.mk:442: force-cargo-library-build] Error 1
  gmake[3]: Leaving directory '/tmp/work/www/firefox/work/build/toolkit/library/rust'
  gmake[2]: *** [/tmp/work/www/firefox/work/firefox-112.0.1/config/recurse.mk:72: toolkit/library/rust/target] Error 2
  gmake[2]: Leaving directory '/tmp/work/www/firefox/work/build'
  gmake[1]: *** [/tmp/work/www/firefox/work/firefox-112.0.1/config/recurse.mk:34: compile] Error 2
  gmake[1]: Leaving directory '/tmp/work/www/firefox/work/build'
  gmake: *** [/tmp/work/www/firefox/work/firefox-112.0.1/config/rules.mk:361: all] Error 2
  *** Error code 2

I wonder if others see this and/or knows where in the twisty maze to
fix.

(Without MAKE_JOBS=1, it seems to build ok and I'm now running with 5 on
a 4-core box.)