Replace hardcoded agda binary by name from package

pkgs/build-support/agda/default.nix

@@ -45,7 +45,7 @@ let
     }:
     let
       libraryFile = mkLibraryFile pkgs;
-      pname = "agdaWithPackages";
+      pname = "${Agda.meta.mainProgram}" + "WithPackages";
       version = Agda.version;
     in
     runCommand "${pname}-${version}"
@@ -68,7 +68,7 @@ let
       }
       ''
         mkdir -p $out/bin
-        makeWrapper ${lib.getExe Agda} $out/bin/agda \
+        makeWrapper ${lib.getExe Agda} $out/bin/${Agda.meta.mainProgram} \
           ${lib.optionalString (ghc != null) ''--add-flags "--with-compiler=${ghc}/bin/ghc"''} \
           --add-flags "--library-file=${libraryFile}"
         ln -s ${lib.getExe' Agda "agda-mode"} $out/bin/agda-mode
@@ -116,7 +116,7 @@ let
         else
           ''
             runHook preBuild
-            agda --build-library
+            ${lib.getExe agdaWithPkgs} --build-library
             runHook postBuild
           '';
 

pkgs/top-level/agda-packages.nix

@@ -27,7 +27,7 @@ let
 
       lib = lib.extend (final: prev: import ../build-support/agda/lib.nix { lib = prev; });
 
-      agda = withPackages [ ];
+      "${Agda.meta.mainProgram}" = withPackages [ ];
 
       standard-library = callPackage ../development/libraries/agda/standard-library { };