zziplib: 0.13.67 -> 0.13.68

Bump zziplib to 0.13.68 to fix multiple CVE issues:

 - CVE-2018-6381
 (https://github.com/gdraheim/zziplib/commit/a803559fa9194be895422ba3684cf6309b6bb598)
 - CVE-2018-6484
 (https://github.com/gdraheim/zziplib/issues/14#issuecomment-363198084)
 - CVE-2018-6540
 (https://github.com/gdraheim/zziplib/commit/72ec933663f738d8e166979aa7fd5590b2104a07)
 - CVE-2018-6541
 (https://github.com/gdraheim/zziplib/issues/16#issuecomment-363197718)
 - CVE-2018-6542
 (https://github.com/gdraheim/zziplib/commit/931f962ddfec0e00d6f486df2c56d9857b55944e)

Unfortunately, getting only those patches is hard, as they're not well
referenced to linked issues. The testsuite checking for vulns
requires network access (so we can't easily test it here).

https://github.com/gdraheim/zziplib/issues/20 might still be an issue,
so keeping this as a TODO here.

pkgs/development/libraries/zziplib/default.nix

@@ -2,20 +2,25 @@
 
 stdenv.mkDerivation rec {
   name = "zziplib-${version}";
-  version = "0.13.67";
+  version = "0.13.68";
 
   src = fetchurl {
     url = "https://github.com/gdraheim/zziplib/archive/v${version}.tar.gz";
-    sha256 = "0802kdxwxx9zanpwb4w4wfi3blwhv0ri05mzdgd35j5sva5ify0j";
+    sha256 = "0chhl6m02562z6c4hjy568mh11pbq2qngw6g2x924ajr8sdr2q4l";
   };
 
   postPatch = ''
     sed -i -e s,--export-dynamic,, configure
   '';
 
+  # TODO: still an issue: https://github.com/gdraheim/zziplib/issues/27
+
   buildInputs = [ docbook_xml_dtd_412 perl python2 zip xmlto zlib ];
 
-  doCheck = true;
+  # tests are broken (https://github.com/gdraheim/zziplib/issues/20),
+  # and test/zziptests.py requires network access
+  # (https://github.com/gdraheim/zziplib/issues/24)
+  doCheck = false;
 
   meta = with stdenv.lib; {
     description = "Library to extract data from files archived in a zip file";