treewide: Get rid of all uses of crossConfig

The hack of using `crossConfig` to enforce stricter handling of
dependencies is replaced with a dedicated `strictDeps` for that purpose.
(Experience has shown that my punning was a terrible idea that made more
difficult and embarrising to teach teach.)

Now that is is clear, a few packages now use `strictDeps`, to fix
various bugs:

 - bintools-wrapper and cc-wrapper

pkgs/development/libraries/fontconfig/2.10.nix

@@ -21,19 +21,10 @@ stdenv.mkDerivation rec {
     "--with-cache-dir=/var/cache/fontconfig"
     "--disable-docs"
     "--with-default-fonts="
+  ] ++ stdenv.lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
+    "--with-arch=${hostPlatform.parsed.cpu.name}"
   ];
 
-  # We should find a better way to access the arch reliably.
-  crossArch = if stdenv.hostPlatform != stdenv.buildPlatform
-    then hostPlatform.parsed.cpu.name
-    else null;
-
-  preConfigure = ''
-    if test -n "$crossConfig"; then
-      configureFlags="$configureFlags --with-arch=$crossArch";
-    fi
-  '';
-
   enableParallelBuilding = true;
 
   doCheck = true;

pkgs/development/libraries/fontconfig/default.nix

@@ -53,19 +53,10 @@ stdenv.mkDerivation rec {
     "--disable-docs"
     # just <1MB; this is what you get when loading config fails for some reason
     "--with-default-fonts=${dejavu_fonts.minimal}"
+  ] ++ stdenv.lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
+    "--with-arch=${hostPlatform.parsed.cpu.name}"
   ];
 
-  # We should find a better way to access the arch reliably.
-  crossArch = if stdenv.hostPlatform != stdenv.buildPlatform
-    then hostPlatform.parsed.cpu.name
-    else null;
-
-  preConfigure = ''
-    if test -n "$crossConfig"; then
-      configureFlags="$configureFlags --with-arch=$crossArch";
-    fi
-  '';
-
   enableParallelBuilding = true;
 
   doCheck = true;