pstack: Remove

It doesn't work anymore. And anyway, this probably shouldn't have been
a package in the first place (it's just some gdb options).

pkgs/development/tools/misc/gdb/pstack.nix

@@ -1,11 +0,0 @@
-{ stdenv, gdb }:
-stdenv.mkDerivation {
-  name = "pstack-20120823";
-  buildCommand = ''
-    mkdir -p $out/bin
-    cat > $out/bin/pstack <<EOF
-    ${gdb}/bin/gdb -ex "set pagination 0" -ex "thread apply all bt" --batch -p \$1
-    EOF
-    chmod a+x $out/bin/pstack
-  '';
-}

pkgs/top-level/all-packages.nix

@@ -4692,8 +4692,6 @@ let
 
   premake = premake4;
 
-  pstack = callPackage ../development/tools/misc/gdb/pstack.nix { };
-
   racerRust = callPackage ../development/tools/rust/racer { rust = rustcMaster; };
 
   radare = callPackage ../development/tools/analysis/radare {