clang: the --sysroot purity trick doesn't take care of the -dynamic-linker setting

Signed-off-by: Shea Levy <shea@shealevy.com>

pkgs/development/compilers/llvm/3.4/clang-purity.patch

@@ -0,0 +1,19 @@
+diff -Naur clang-3.4-orig/lib/Driver/Tools.cpp clang-3.4/lib/Driver/Tools.cpp
+--- clang-3.4-orig/lib/Driver/Tools.cpp	2013-12-08 21:59:27.000000000 -0500
++++ clang-3.4/lib/Driver/Tools.cpp	2014-01-27 12:48:29.421872597 -0500
+@@ -6477,15 +6477,6 @@
+     }
+   }
+ 
+-  if (ToolChain.getArch() == llvm::Triple::arm ||
+-      ToolChain.getArch() == llvm::Triple::thumb ||
+-      (!Args.hasArg(options::OPT_static) &&
+-       !Args.hasArg(options::OPT_shared))) {
+-    CmdArgs.push_back("-dynamic-linker");
+-    CmdArgs.push_back(Args.MakeArgString(
+-        D.DyldPrefix + getLinuxDynamicLinker(Args, ToolChain)));
+-  }
+-
+   CmdArgs.push_back("-o");
+   CmdArgs.push_back(Output.getFilename());
+ 

pkgs/development/compilers/llvm/3.4/clang.nix

@@ -15,7 +15,7 @@ stdenv.mkDerivation {
     (cd llvm-${version} && patch -Np1 -i ${./llvm-separate-build.patch})
   '';
 
-  patches = [ ./clang-separate-build.patch ];
+  patches = [ ./clang-separate-build.patch ./clang-purity.patch ];
 
   buildInputs = [ cmake libedit libxml2 ];