Adding a new version of the gcc-wrapper, named gcc-wrapper2, in order not to rebuild

stdenv.

In this gcc-wrapper2 I made the ld-wrapper.sh to handle the linking with shared
objects through direct pass as ld command arguments of the absolute path to shared
objects, instead of using the -L/-l combinations.

cmake 'FindXXX.cmake' modules make a strong usage of the dynamic linking directly
passing the absolute path to the shared object to the linker, and as our wrapper did
not add any -rpath for those, writting the nix expressions for some cmake packages
resulted in a lot of tricks, compared to using this gcc-wrapper2.

This gcc-wrapper2/ld-wrapper.sh should become the gcc-wrapper/ld-wrapper in a
stdenv update.

I also updated some cmake expressions to use this gcc-wrapper2, and reduced its
tricks.

I also updated the cmake setup-hook for it to make cmake not touch any rpath decided
at build time, when running the 'make install' of makefiles created by cmake.

svn path=/nixpkgs/trunk/; revision=18885

pkgs/development/tools/build-managers/cmake/setup-hook.sh

@@ -32,6 +32,9 @@ cmakeConfigurePhase()
         cmakeFlags="-DCMAKE_INSTALL_PREFIX=$prefix $cmakeFlags"
     fi
 
+    # Avoid cmake resetting the rpath of binaries, on make install
+    cmakeFlags="-DCMAKE_SKIP_BUILD_RPATH=ON $cmakeFlags"
+
     echo "cmake flags: $cmakeFlags ${cmakeFlagsArray[@]}"
 
     cmake ${cmakeDir:-.} $cmakeFlags ${cmakeFlagsArray[@]}