neovim: remove confusing neovim parameter

[teto]

The neovim package refers to itself, hopefully it is shadowed by a
function parameter but it is confusing, let's remove it.

Motivation for this change

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

---

[Mic92]

@GrahamcOfBorg build neovim

[GrahamcOfBorg]

Success on x86_64-linux (full log)

Partial log (click to expand)

copying path '/nix/store/hwa2zafmn2azpsqqzmi0h6pn58hcnll3-xsel-unstable-2016-09-02' from 'https://cache.nixos.org'...
copying path '/nix/store/3ki26cxx4lip898czmmhjxfl2a5c04kj-python2.7-neovim-0.2.0' from 'https://cache.nixos.org'...
copying path '/nix/store/b9xsscjrs0qabvg52j29ikk8wjb8z1ij-python3.6-neovim-0.2.0' from 'https://cache.nixos.org'...
copying path '/nix/store/kp86sngc2cgrndnmmswcz8pz3s0ndcsv-neovim-unwrapped-0.2.2' from 'https://cache.nixos.org'...
copying path '/nix/store/2midfw9s88qz344cjwrfj35a15jy3agg-python-2.7.14-env' from 'https://cache.nixos.org'...
copying path '/nix/store/pbhxrvij92p5agc9jr5zyrbr6wm6yxpm-python3-3.6.4-env' from 'https://cache.nixos.org'...
copying path '/nix/store/1lx55vcsyrzddpcdcynz3004k47kc6lc-ruby2.3.6-neovim-0.6.2' from 'https://cache.nixos.org'...
copying path '/nix/store/y5r6z66gh0krn55zl0997z7dyy7msyg0-neovim-ruby-env' from 'https://cache.nixos.org'...
copying path '/nix/store/ljfy19dczmjgkdyfb377f14cvzb9g8i7-neovim' from 'https://cache.nixos.org'...
/nix/store/ljfy19dczmjgkdyfb377f14cvzb9g8i7-neovim

[GrahamcOfBorg]

Failure on aarch64-linux (full log)

Partial log (click to expand)

	/build/source/src/nvim/generators/gen_declarations.lua:232: in main chunk
	[C]: at 0x004052e0
make[2]: *** [src/nvim/CMakeFiles/nvim.dir/build.make:217: src/nvim/auto/eval.c.generated.h] Error 1
make[1]: *** [CMakeFiles/Makefile2:2451: src/nvim/CMakeFiles/nvim.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
[  0%] Built target tty-test
make: *** [Makefile:152: all] Error 2
builder for '/nix/store/myy4p9na3hkwsvi66qgwm02zv1hyxsbc-neovim-unwrapped-0.2.2.drv' failed with exit code 2
cannot build derivation '/nix/store/zj45llvn9nvffd0h1jzpjqcxgvnzjxkj-neovim.drv': 1 dependencies couldn't be built
error: build of '/nix/store/zj45llvn9nvffd0h1jzpjqcxgvnzjxkj-neovim.drv' failed

[GrahamcOfBorg]

Success on x86_64-darwin (full log)

Partial log (click to expand)

copying path '/nix/store/gap51f9xd4hwghm07cz0clq4pc449jr4-python3.6-greenlet-0.4.10' from 'https://cache.nixos.org'...
copying path '/nix/store/gn9jg3gq3rbx4320pxw7ygwx1di8qisj-ruby2.3.6-neovim-0.6.2' from 'https://cache.nixos.org'...
copying path '/nix/store/d1x76lmx8x9glsgil2fl10rnqdjbbgjw-python3.6-neovim-0.2.0' from 'https://cache.nixos.org'...
copying path '/nix/store/1rh9x951m9ha4bzzd0a00ad6bfynanf4-neovim-unwrapped-0.2.2' from 'https://cache.nixos.org'...
copying path '/nix/store/pxwj3nvbqi91w2afn722bs7b9zakx0c8-python3-3.6.4-env' from 'https://cache.nixos.org'...
copying path '/nix/store/qr5bd7j45a7qx5zcfpcdnf2s02gib2bj-neovim-ruby-env' from 'https://cache.nixos.org'...
copying path '/nix/store/sfxdsg7mrj4giscph3aaxc5w5rck77f1-python2.7-neovim-0.2.0' from 'https://cache.nixos.org'...
copying path '/nix/store/1fkz4lnzf7jg9d1bbzyv9crn8dc4vlz1-python-2.7.14-env' from 'https://cache.nixos.org'...
copying path '/nix/store/bvfrzk21kv4w3fy7gh38byrfvbqrsdap-neovim' from 'https://cache.nixos.org'...
/nix/store/bvfrzk21kv4w3fy7gh38byrfvbqrsdap-neovim