Proposal: hide unavoidable compilations by default

[swedebugia]

Hi

I tested installing extremetuxracer today.

I got this:

substitute: updating substitutes from 'https://ci.guix.info'... 100.0%
The following derivations would be built:
   /gnu/store/jyg5na6m93s2m40ma96l4809f5cnbd2a-profile.drv
   /gnu/store/zcyshai941cb88326rggrcv2sqxbl5dl-gtk-im-modules.drv
   /gnu/store/z2lay5k0hm9xsr0ds34iyicw9r12cpvi-ca-certificate-bundle.drv
   /gnu/store/n4dff9vfgzrmkcvyh3nhypd64p0bbvw1-xdg-mime-database.drv
   /gnu/store/j5pbmdjqsb9dv3chjfkk0b8i0h7kr4sw-xdg-desktop-database.drv
   /gnu/store/hs46q0lhmm7xhjgygdg175v4c6jmvjvc-fonts-dir.drv
   /gnu/store/hdifcszmlf1gwd2q0zg4n7zkabzm1bx0-glib-schemas.drv
   /gnu/store/4idc38h10bcz1ln97pakaxkr3gdn9j2p-gtk-icon-themes.drv
   /gnu/store/0fs4jqxrnwlgwq3dnyzpd00ww68l2k0c-info-dir.drv
   /gnu/store/9xydhzf9810vljhyzcackgg34hvqmj7v-extremetuxracer-0.7.5.drv
   /gnu/store/apsn4m9fnv7927dnlj9wya39035l4i69-manual-database.drv
44.7 MB would be downloaded:
   /gnu/store/ia3zw1nb1vppscl9lpj3v5d8r3p4zv9q-etr-0.7.5.tar.xz
   /gnu/store/yyn8g8am7y9xl4dhrzb6klrmaqwjl2mk-sfml-2.5.1

Many of the things to be built are unavoidable internals of guix that 
are not relevant to the user.

I suggest we hide them unless given a flag like --show-all-drv

This is after hiding them:

substitute: updating substitutes from 'https://ci.guix.info'... 100.0%
The following derivations would be built:
   /gnu/store/9xydhzf9810vljhyzcackgg34hvqmj7v-extremetuxracer-0.7.5.drv
44.7 MB would be downloaded:
   /gnu/store/ia3zw1nb1vppscl9lpj3v5d8r3p4zv9q-etr-0.7.5.tar.xz
   /gnu/store/yyn8g8am7y9xl4dhrzb6klrmaqwjl2mk-sfml-2.5.1

--
Cheers Swedebugia