Merge pull request #308476 from LordGrimmauld/cpupower_meta

cpupower: add meta.mainProgram

pkgs/os-specific/linux/cpupower/default.nix

···
     description = "Tool to examine and tune power saving features";
     homepage = "https://www.kernel.org/";
     license = licenses.gpl2;
+    mainProgram = "cpupower";
     platforms = platforms.linux;
   };
 }