nix: hack static-haskell-nix for updated nixpkgs

This patches static-haskell-nix to work for building postgrest
with updated nixpkgs (from ~202203):

- The ncurses 'enableStatic' argument doesn't exist anymore.
  We use the vanilla package instead, which seems to work fine.
- The 'isExecutable' check fails with a strange error related
  to trying to override 'mkDerivation'.
  We patch 'isExecutable' to check explicitly whether we're building
  postgrest. ('isExecutable' is used to determine whether to build
  a package statically.)

nix/patches/static-haskell-nix-ncurses.patch

@@ -0,0 +1,13 @@
+diff --git a/survey/default.nix b/survey/default.nix
+index 46d8066..a47f214 100644
+--- a/survey/default.nix
++++ b/survey/default.nix
+@@ -1519,7 +1519,7 @@ let
+                   [
+                     "--enable-executable-static" # requires `useFixedCabal`
+                     # `enableShared` seems to be required to avoid `recompile with -fPIC` errors on some packages.
+-                    "--extra-lib-dirs=${final.ncurses.override { enableStatic = true; enableShared = true; }}/lib"
++                    "--extra-lib-dirs=${final.ncurses}/lib"
+                   ]
+                   # TODO Figure out why this and the below libffi are necessary.
+                   #      `working` and `workingStackageExecutables` don't seem to need that,