Merge pull request #40929 from obsidiansystems/cross-ghc-for-master

ghc, haskell infra: #40642 direct to master

pkgs/development/haskell-modules/lib.nix

@@ -131,6 +131,8 @@ rec {
    */
   appendConfigureFlag = drv: x: overrideCabal drv (drv: { configureFlags = (drv.configureFlags or []) ++ [x]; });
 
+  appendBuildFlag = drv: x: overrideCabal drv (drv: { buildFlags = (drv.buildFlags or []) ++ [x]; });
+  appendBuildFlags = drv: xs: overrideCabal drv (drv: { buildFlags = (drv.buildFlags or []) ++ xs; });
   /* removeConfigureFlag drv x is a Haskell package like drv, but with
      all cabal configure arguments that are equal to x removed.