blast: Package official ncbi-blast package

Based on initial work by Armin.

pkgs/all-packages.nix

@@ -4,6 +4,10 @@
 #
 self: super: pkgs: with pkgs; {
 
+  blast = callPackage ./blast {
+    stdenv = overrideCC stdenv gcc5;
+  };
+
   cryptominisat = callPackage ./cryptominisat.nix { };
 
   #firedrake = callPackage ./firedrake { };