gcc-*: homogenize and cleanup expressions with a mass rebuild

pkgs/development/compilers/gcc/4.8/default.nix

@@ -206,15 +206,22 @@ stdenv.mkDerivation ({
     ++ (optional (perl != null) perl)
     ++ (optional javaAwtGtk pkgconfig);
 
+  # For building runtime libs
+  depsBuildTarget =
+    if hostPlatform == buildPlatform then [
+      targetPackages.stdenv.cc.bintools # newly-built gcc will be used
+    ] else assert targetPlatform == hostPlatform; [ # build != host == target
+      stdenv.cc
+    ];
+
   buildInputs = [
     gmp mpfr libmpc libelf
+    targetPackages.stdenv.cc.bintools # For linking code at run-time
   ] ++ (optional (cloog != null) cloog)
     ++ (optional (isl != null) isl)
     ++ (optional (zlib != null) zlib)
     ++ (optionals langJava [ boehmgc zip unzip ])
     ++ (optionals javaAwtGtk ([ gtk2 libart_lgpl ] ++ xlibs))
-    ++ (optionals (targetPlatform != hostPlatform) [targetPackages.stdenv.cc.bintools])
-
     # The builder relies on GNU sed (for instance, Darwin's `sed' fails with
     # "-i may not be used with stdin"), and `stdenvNative' doesn't provide it.
     ++ (optional hostPlatform.isDarwin gnused)