ethash: remove buildInputs

When reviewing #98054, I noticed that this package has a bunch of
buildInputs that are unused. There are no references to OpenCL, mesa,
boost, cryptopp, or openmpi in the source code. The package compiles
fine with these buildInputs removed.

pkgs/development/libraries/ethash/default.nix

@@ -1,5 +1,4 @@
-{ stdenv, fetchFromGitHub, cmake, boost, cryptopp, opencl-headers, opencl-info,
-  openmpi, ocl-icd, mesa, gbenchmark, gtest }:
+{ stdenv, fetchFromGitHub, cmake, gbenchmark, gtest }:
 
 stdenv.mkDerivation rec {
   pname = "ethash";
@@ -17,16 +16,6 @@ stdenv.mkDerivation rec {
     cmake
   ];
 
-  buildInputs = [
-    boost
-    cryptopp
-    opencl-headers
-    opencl-info
-    openmpi
-    ocl-icd
-    mesa
-  ];
-
   checkInputs = [
     gbenchmark
     gtest