nongnu: Remove unneeded packages from mozilla.scm.
* nongnu/packages/mozilla.scm (rust-proc-macro2-1.0.43, rust-syn-1.0.99,
rust-windows-x86-64-msvc-0.36, rust-windows-x86-64-gnu-0.36,
rust-windows-i686-msvc-0.36, rust-windows-i686-gnu-0.36,
rust-windows-aarch64-msvc-0.36, rust-windows-sys-0.36, rust-hashbrown-0.12,
rust-object-0.29, rust-object-0.27, rust-gimli-0.26, rust-addr2line-0.17,
rust-backtrace-0.3.66, rust-parking-lot-core-0.9, rust-once-cell-1.13.0):
Remove variables (added to upstream Guix).
(rust-clap-derive-3.2.15, rust-clap-3.2.16, rust-cbindgen-0.24)[cargo-inputs]:
Adjust to upstream package names.