Figuring out linking for Rust packages

[atomicules <base%atomicules.co.uk@localhost>]

I'm trying to translate this:

https://atomicules.co.uk/2019/01/17/Building-Spotifyd-on-NetBSD.html

Into pkgsrc:

https://wip.pkgsrc.org/cgi-bin/gitweb.cgi?p=pkgsrc-wip.git;a=tree;f=spotifyd;h=8d79607930af6ec69d05354ef9a70a5e9ac52462;hb=HEAD

but am stuck on figuring out linking stuff. The right paths aren't.
getting passed to cc for the linking phase and I end up with:

   error: linking with `cc` failed: exit code: 1
     |
       = note: "cc" "-Wl,--as-needed" "-Wl,-z,noexecstack" "-m64" "-L".
       "/usr/pkg/lib/rustlib/x86_64-unknown-netbsd/lib"

       [removing most of this, but it does have:]

        "-L" "/usr/lib"

       [but /usr/pkg/lib never makes an appearance]

       "-Wl,-Bdynamic" "-lpulse" "-lpulse-simple" "-lc" "-lutil" "-lutil".
       "-lpthread" "-lgcc_s" "-lm" "-lutil" "-lutil"
         = note: ld: cannot find -lpulse
                 ld: cannot find -lpulse-simple

As far as I can tell everything is there in the MAKE_ENV:

	[...]
	LDFLAGS=-L/usr/pkg/lib\ -Wl,-R/usr/pkg/lib\ -L/usr/pkg/lib/pulseaudio\
	-Wl,-R/usr/pkg/lib/pulseaudio\ -L/usr/X11R7/lib\ -Wl,-R/usr/X11R7/lib\
	-L/usr/lib\ -Wl,-R/usr/lib LINKER_RPATH_FLAG=-R
	[...]

I.e. I see /usr/pkg/lib, although perhaps somehow is getting overridden by that
later `-R/usr/lib`?

I'm stumped so would appreciate any ideas/suggestions. I'm pretty sure it's
something dead simple I'm missing - I just haven't been able to figure it out.
I've mostly copied the tealdeer makefile as I had no idea it was even possible
to do Rust packages.

This is on NetBSD 8, amd64

_Worth mentioning, that if you try to build this, it needs a tweak to
`lang/rust/cargo.mk`, see the TODO file_