powertop: Patch out path to /sbin/modprobe (close #8702)

The modprobe call is made via system(), so an absolute path is not
needed if modprobe is in PATH. Which it is by default at least in
NixOS and Arch.

Fixes #5424.

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

···
 
   buildInputs = [ gettext libnl ncurses pciutils pkgconfig zlib ];
 
+  patchPhase = ''
+    substituteInPlace src/main.cpp --replace "/sbin/modprobe" "modprobe"
+  '';
+
   meta = {
     description = "Analyze power consumption on Intel-based laptops";
     license = stdenv.lib.licenses.gpl2;