Configure Haskell build system to forego tests, benchmarks, profiling

Cherry-picked from tahoe-lafs-mobile commit
e6bba36221f22cfc744cb02fa23265d504d481da .

obelisk/haskell-overrides.nix

@@ -2,6 +2,19 @@
 self: super:
 with pkgs.haskell.lib; {
 
+  # Sometimes, I just want fast build times, and I don't care about tests,
+  # documentation, or getting stuff from a cache.
+  # From https://discourse.nixos.org/t/nix-haskell-development-2020/6170/2
+  mkDerivation = args: super.mkDerivation (args // {
+      doCheck = false;
+      doHaddock = false;
+      enableLibraryProfiling = false;
+      enableExecutableProfiling = false;
+      # jailbreak = true; # Maybe a bit too much hehe
+      # Disable compiler optimizations for faster compilation:
+      # buildFlags = [ "--ghc-options=-O0" ];
+    });
+
   # Use our fork of android-activity which adds support for VIEW intents.
   android-activity = import
     (nix-thunk.thunkSource ./dep/android-activity)