treewide: Get rid of most parseDrvName without breaking compat

That is because this commit should be merged to both master and
release-19.09.

nixos/modules/system/boot/loader/grub/grub.nix

@@ -47,8 +47,8 @@ let
       grub = f grub;
       grubTarget = f (grub.grubTarget or "");
       shell = "${pkgs.runtimeShell}";
-      fullName = (builtins.parseDrvName realGrub.name).name;
-      fullVersion = (builtins.parseDrvName realGrub.name).version;
+      fullName = lib.getName realGrub;
+      fullVersion = lib.getVersion realGrub;
       grubEfi = f grubEfi;
       grubTargetEfi = if cfg.efiSupport && (cfg.version == 2) then f (grubEfi.grubTarget or "") else "";
       bootPath = args.path;