firedrake: Moved to new overlay system and shared sub-scope

Firedrake contains a ton of inter-connected dependencies, many of
which are either firedrake specific or forked versions of upstream
packages.  Cleaner to create a firedrake sub-scope for all these.

pkgs/firedrake/petsc.nix

@@ -0,0 +1,53 @@
+{ stdenv, callPackage, writeText, fetchFromGitHub, python, gfortran
+, openmpi, blas, liblapack, hdf5, netcdf, eigen
+, sowing, metis, hypre, parmetis, exodus }:
+
+stdenv.mkDerivation rec {
+  version = "156a1856fd44f55220132393778f0fda1e6096e3";
+  name = "firedrake-petsc-${version}";
+
+  src = fetchFromGitHub {
+    owner = "firedrakeproject";
+    repo = "petsc";
+    rev = "${version}";
+    sha256 = "1fmkd818idbiwbr6q9bmsxgwsc7igk13amfvb160llvsj32i93s9";
+  };
+
+  buildInputs = [
+    sowing
+    metis
+    parmetis
+    hypre
+    exodus
+    python
+    gfortran
+    openmpi
+    blas
+    liblapack
+    hdf5
+    netcdf
+    eigen
+  ];
+
+  postPatch = "patchShebangs .";
+
+  configureFlags = [
+    "--with-sowing-dir=${sowing}"
+    "--with-hdf5-dir=${hdf5}"
+    "--with-netcdf-dir=${netcdf}"
+    "--with-metis-dir=${metis}"
+    "--with-parmetis-dir=${parmetis}"
+    "--with-hypre-dir=${hypre}"
+    "--with-exodusii-dir=${exodus}"
+    "--with-eign-dir=${eigen}"
+    "--with-64-bit-indices"
+  ];
+
+  setupHook = writeText "setupHook.sh" "export PETSC_DIR=@out@";
+
+  meta = with stdenv.lib; {
+    homepage = "https://github.com/firedrakeproject/petsc";
+    description = "A suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations.";
+    license = licenses.bsd2;
+  };
+}