llvm: Bring back old expressions for llvm & clang 3.[123].
Idris: Build with llvm backend and libffi support

Signed-off-by: Shea Levy <shea@shealevy.com>
llvm: Enable also building of LLVM 3.[12] & Clang 3.[123].
clang_31: Allow clang to find system includes in gcc dirs.
Backported fix.
LLVM: Allow building gold plugins together with llvm 3.{1,2}.
Merge branch 'vlstill-llvm-multivers'
Unmaintain old llvm versions

Signed-off-by: Shea Levy <shea@shealevy.com>
haskell-highlighting-kate: re-generate with cabal2nix
haskell-happstack-server: re-generate with cabal2nix
idris: re-generate with cabal2nix
trifecta-1.2: re-generate with cabal2nix