Hello,

Here's a patch that adds a "lib" output to cross-gcc. This was indeed
quite tricky!

Anyway, with this patch the closure of "hello" for aarch64-linux-gnu is
reduced from 469 MiB to 187 MiB.

I think we can go further.

--8<---------------cut here---------------start------------->8---
mathieu@elbruz ~/guix [env]$ guix size /gnu/store/14ygibryjr7mcly0q9mb8306hlg16nhq-hello-2.10
store item                                                       total    self
/gnu/store/vm2gaw5jk1zr1x9qzj4z52qjxvrh0nk9-glibc-cross-aarch64-linux-gnu-2.31   158.9    71.4  38.2%
/gnu/store/w00jb174abikqpznadwzvvgwl3r7qfzd-glibc-2.31              38.4    36.7  19.6%
/gnu/store/08vqg0s77dnff7rz90b0h87n2rfyaszg-gcc-7.5.0-lib           71.0    32.6  17.5%
/gnu/store/vqsixs9ks4chpjynhizkpdd1gdshv87h-gcc-cross-aarch64-linux-gnu-7.5.0-lib   186.8    27.9  14.9%
/gnu/store/fgrpk8r46k34pyqv6xkbi8gbv997dbpx-gcc-cross-sans-libc-aarch64-linux-gnu-7.5.0-lib    80.8     9.8   5.2%
/gnu/store/zf5603c5l6ilgyg35gqfkn82v3k9hbri-linux-libre-headers-cross-aarch64-linux-gnu-5.4.20     5.1     5.1   2.7%
/gnu/store/6hhsxa3vvbh8gvcfjw4k5sfk1qrhkcrf-bash-static-5.0.16       1.6     1.6   0.9%
/gnu/store/nvc3r588745kkj159lm1pa4xz5g99rqd-bash-static-5.0.16       1.6     1.6   0.9%
/gnu/store/14ygibryjr7mcly0q9mb8306hlg16nhq-hello-2.10             187.0     0.2   0.1%
total: 187.0 MiB
--8<---------------cut here---------------end--------------->8---

There are still references to native glibc/gcc and two different bash,
that may be removed?

WDYT?

Thanks,

Mathieu