Run ./nix/sync-with-upstream after pull!

[Ludovic Courtès]

Hi!

After pulling commit 0c5028f, you’ll should get an error like this when
building:

--8<---------------cut here---------------start------------->8---
nix/libutil/hash.cc:244:13: error: member ‘guix_hash_context nix::Ctx::md5’ 
with constructor not allowed in union
     MD5_CTX md5;
             ^
nix/libutil/hash.cc:244:13: note: unrestricted unions only available with 
-std=c++11 or -std=gnu++11
--8<---------------cut here---------------end--------------->8---

Make sure to run ./nix/sync-with-upstream to fix that (this script has
an additional patch rule to fix that.)

Thanks,
Ludo’.