Fix GPI-2 and enable TAGASPI

The rdma-core driver.h include is no longer installed:

 56dd87acd2

So ibv_read_sysfs_file() is not defined. As the symbols is still
distributed, we simply add the missing prototype manually.

Similarly, the gaspi_size_t gaspi_get_system_mem() function is not
available from the gaspi public headers, so we define it in the
max_mem.c test.

Fixes: rarias/bscpkgs#7

flake.nix

@@ -13,8 +13,5 @@
       bscOverlay = import ./overlay.nix;
       overlays.default = self.bscOverlay;
       legacyPackages.x86_64-linux = pkgs;
-
-      # propagate nixpkgs lib, so we can do bscpkgs.lib
-      inherit (nixpkgs) lib;
     };
 }

overlay.nix

@@ -1,19 +1,15 @@
 final: /* Future last stage */
 prev:  /* Previous stage */
 
-let
-  inherit (prev.lib) collect isDerivation mapAttrs;
+with final.lib;
 
-  inherit (final) callPackage;
+let
+  callPackage = final.callPackage;
 
   mkDeps = name: pkgs: final.runCommand name { }
     "printf '%s\n' ${toString (collect (x: x ? outPath) pkgs)} > $out";
 
-  mkStrict = drv: if (isDerivation drv && drv ? overrideAttrs && !(drv ? strictDeps))
-    then drv.overrideAttrs { strictDeps = true; }
-    else drv;
-
-  bscPkgs = mapAttrs (_: mkStrict) {
+  bscPkgs = {
     bench6 = callPackage ./pkgs/bench6/default.nix { };
     bigotes = callPackage ./pkgs/bigotes/default.nix { };
     clangOmpss2 = callPackage ./pkgs/llvm-ompss2/default.nix { };