firefox build problem with MAKE_JOBS=1

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

The build of firefox overrides the parallelization of the cargo/rust part.

patches/patch-config_makefiles_rust.mk:+cargo_build_flags += -j1

However, when MAKE_JOBS is already set to one, this breaks:

toolkit/library/rust/force-cargo-library-build
/usr/pkg/bin/cargo rustc  --release --frozen --manifest-path /scratch/www/firefox/work/firefox-94.0.2/toolkit/library/rust/Cargo.toml -vv -j1 -j1 --lib --target=aarch64-unknown-netbsd --features 'moz_places webrtc glean_with_gecko glean_disable_upload with_dbus' --  -Clto
error: The argument '--jobs <N>' was provided more than once, but cannot be used multiple times

USAGE:
    cargo rustc --features <FEATURES>... --frozen --jobs <N> --lib --manifest-path <PATH> --release --target <TRIPLE>... --verbose

For more information try --help


Does anyone have an idea how to fix that?

(My workaround was to increase MAKE_JOBS to 2 and if the machine runs
out of RAM, I'll set it to 1 again.)
 Thomas