Update `NEWS' and `TODO'.
Merge branch 'master' into core-updates
Conflicts:
gnu/packages/make-bootstrap.scm
Update upstream Nix sub-module.
* nix-upstream: Update.
* NEWS: Mention multiple-derivation output bug.
guix gc: Add `--requisites'.
* guix/scripts/gc.scm (show-help, %options): Add `--requisites'.
(guix-gc): Handle it.
* doc/guix.texi (Invoking guix gc): Document `--requisites'.
* NEWS: Update.
doc: Update `NEWS'.
* NEWS: Update.
doc: Update `NEWS'.
* NEWS: Populate.
Update `NEWS'.
* NEWS: Update.
build: Use Automake's `gnu' option.
* configure.ac: Use Automake's `gnu' option.
* ChangeLog, NEWS: New files.