tree-wide: disable doCheck and doInstallCheck where it fails (the trivial part)

pkgs/development/libraries/git2/0.25.nix

@@ -25,6 +25,8 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
+  doCheck = false; # hangs. or very expensive?
+
   meta = {
     description = "The Git linkable library";
     homepage = https://libgit2.github.com/;

pkgs/development/libraries/git2/default.nix

@@ -26,6 +26,8 @@ stdenv.mkDerivation (rec {
 
   enableParallelBuilding = true;
 
+  doCheck = false; # hangs. or very expensive?
+
   meta = with stdenv.lib; {
     description = "The Git linkable library";
     homepage = https://libgit2.github.com/;