Drop external*Inputs from packages

Get rid of some manual package set resolution in favor of splicing
again, too.

Co-authored-by: John Ericson <John.Ericson@Obsidian.Systems>

src/libstore-tests/package.nix

@@ -42,20 +42,16 @@ mkMesonExecutable (finalAttrs: {
     (fileset.fileFilter (file: file.hasExt "hh") ./.)
   ];
 
-  # Hack for sake of the dev shell
-  passthru.externalBuildInputs = [
+  buildInputs = [
     sqlite
     rapidcheck
     gtest
-  ]
-  ++ lib.optionals withBenchmarks [
-    gbenchmark
-  ];
-
-  buildInputs = finalAttrs.passthru.externalBuildInputs ++ [
     nix-store
     nix-store-c
     nix-store-test-support
+  ]
+  ++ lib.optionals withBenchmarks [
+    gbenchmark
   ];
 
   mesonFlags = [