Merge branch 'core-updates'

Conflicts:
	gnu/packages/gnunet.scm

gnu: pspp: Add input cairo.

* gnu/packages/maths.scm (pspp): Add cairo and further necessary inputs.
* gnu/packages/patches/pspp-tests.patch: New file, thanks to
  John Darrington <john@darrington.wattle.id.au>.
* gnu-system.am (dist_patch_DATA): Register patch.