Rebasing core-updates-next branch

[Manolis Ragkousis]

Hello Guix,

Core-updates-next has not been updated for some time so I think it's
time to do that.  I was planning to rebase core-updates-next on
core-updates and create a new core-updates-next.

There is a problem though. Rebasing changes the pgp signature of the
commit. The affected commits are the ones below.

a08539d gnu: guile: Use "site-ccache" for the compiled search path.
14af4d1 build: Correctly determine the system type for GNU/Hurd systems.
5b32f07 gnu: wrap-python3: Create more symlinks.
788eb97 gnu: sqlite: Update to 3.13.0.
bd46fdc utils: Fix 'modify-phases' docstring.
d35bc36 gnu: curl: Update to 7.49.1.
98e8dc6 packages: Use '--no-backup-if-mismatch' for patching.

I have cc'ed the authors of those commits.  If you are okay with it, I
will sign those commits with my key and push the new core-udpates-next.

Thank you,
Manolis