nimPackages.nimBuilder: collect deps from $pkgsHostTarget

pkgs/development/nim-packages/build-nim-package/default.nix

···
 
   configurePhase = if isNull configurePhase then ''
     runHook preConfigure
-    find $NIX_BUILD_TOP -name .attrs.json
+    export NIX_NIM_BUILD_INPUTS=''${pkgsHostTarget[@]} $NIX_NIM_BUILD_INPUTS
     nim_builder --phase:configure
     runHook postConfigure
   '' else

pkgs/development/nim-packages/nim_builder/nim_builder.nim

···
   for def in getEnv("nimDefines").split:
     if def != "":
       switch("define", def)
-  for input in getEnv("buildInputs").split:
+  for input in getEnv("NIX_NIM_BUILD_INPUTS").split:
     if input != "":
       for nimbleFile in walkFiles(input / "*.nimble"):
         let inputSrc = normalizedPath(