treewide: Remove stdenv.isCross

I *want* cross-specific overrides to be verbose, so I rather not have
this shorthand. This makes the syntactic overhead more proportional to
the maintainence cost. Hopefully this pushes people towards fewer
conditionals and more abstractions.

pkgs/development/tools/build-managers/meson/default.nix

@@ -1,7 +1,6 @@
-{ lib, python3Packages, stdenv, targetPlatform, writeTextDir, substituteAll }: let
-  targetPrefix = lib.optionalString stdenv.isCross
-                   (targetPlatform.config + "-");
-in python3Packages.buildPythonApplication rec {
+{ lib, python3Packages, stdenv, targetPlatform, writeTextDir, substituteAll }:
+
+python3Packages.buildPythonApplication rec {
   version = "0.46.1";
   pname = "meson";
 
@@ -48,10 +47,10 @@ in python3Packages.buildPythonApplication rec {
 
   crossFile = writeTextDir "cross-file.conf" ''
     [binaries]
-    c = '${targetPrefix}cc'
-    cpp = '${targetPrefix}c++'
-    ar = '${targetPrefix}ar'
-    strip = '${targetPrefix}strip'
+    c = '${stdenv.cc.targetPrefix}cc'
+    cpp = '${stdenv.cc.targetPrefix}c++'
+    ar = '${stdenv.cc.bintools.targetPrefix}ar'
+    strip = '${stdenv.cc.bintools.targetPrefix}strip'
     pkgconfig = 'pkg-config'
 
     [properties]
@@ -69,7 +68,9 @@ in python3Packages.buildPythonApplication rec {
   # checkInputs = [ ninja pkgconfig ];
   # checkPhase = "python ./run_project_tests.py";
 
-  inherit (stdenv) cc isCross;
+  inherit (stdenv) cc;
+
+  isCross = stdenv.buildPlatform != stdenv.hostPlatform;
 
   meta = with lib; {
     homepage = http://mesonbuild.com;