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/interpreters/guile/1.8.nix

@@ -16,7 +16,11 @@ stdenv.mkDerivation rec {
   setOutputFlags = false; # $dev gets into the library otherwise
 
   # GCC 4.6 raises a number of set-but-unused warnings.
-  configureFlags = [ "--disable-error-on-warning" ];
+  configureFlags = [ "--disable-error-on-warning" ]
+    # Guile needs patching to preset results for the configure tests about
+    # pthreads, which work only in native builds.
+    ++ stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform)
+                          "--with-threads=no";
 
   depsBuildBuild = [ buildPackages.stdenv.cc ]
     ++ stdenv.lib.optional (hostPlatform != buildPlatform)
@@ -34,17 +38,8 @@ stdenv.mkDerivation rec {
     libtool
   ];
 
-
   patches = [ ./cpp-4.5.patch ];
 
-  # Guile needs patching to preset results for the configure tests
-  # about pthreads, which work only in native builds.
-  preConfigure = ''
-    if test -n "$crossConfig"; then
-      configureFlags="--with-threads=no $configureFlags"
-    fi
-  '';
-
   preBuild = ''
     sed -e '/lt_dlinit/a  lt_dladdsearchdir("'$out/lib'");' -i libguile/dynl.c
   '';