treewide: add meta.mainProgram (#248750)

pkgs/applications/misc/goldendict/default.nix

@@ -63,6 +63,7 @@ stdenv.mkDerivation rec {
     homepage = "http://goldendict.org/";
     description = "A feature-rich dictionary lookup program";
     platforms = with platforms; linux ++ darwin;
+    mainProgram = "goldendict";
     maintainers = with maintainers; [ gebner astsmtl sikmir ];
     license = licenses.gpl3Plus;
   };

pkgs/applications/video/dmlive/default.nix

@@ -37,6 +37,7 @@ rustPlatform.buildRustPackage rec {
     description = "A tool to play and record videos or live streams with danmaku";
     homepage = "https://github.com/THMonster/dmlive";
     license = licenses.mit;
+    mainProgram = "dmlive";
     maintainers = with maintainers; [ nickcao ];
   };
 }

pkgs/tools/misc/xclip/default.nix

@@ -19,6 +19,7 @@ stdenv.mkDerivation rec {
     description = "Tool to access the X clipboard from a console application";
     homepage = "https://github.com/astrand/xclip";
     license = lib.licenses.gpl2;
+    mainProgram = "xclip";
     platforms = lib.platforms.all;
   };
 }

pkgs/tools/security/age/default.nix

@@ -57,6 +57,7 @@ buildGoModule rec {
     homepage = "https://age-encryption.org/";
     description = "Modern encryption tool with small explicit keys";
     license = licenses.bsd3;
+    mainProgram = "age";
     maintainers = with maintainers; [ tazjin ];
   };
 }

pkgs/tools/typesetting/tectonic/default.nix

@@ -46,6 +46,7 @@ rustPlatform.buildRustPackage rec {
     homepage = "https://tectonic-typesetting.github.io/";
     changelog = "https://github.com/tectonic-typesetting/tectonic/blob/tectonic@${version}/CHANGELOG.md";
     license = with licenses; [ mit ];
+    mainProgram = "tectonic";
     maintainers = with maintainers; [ lluchs doronbehar ];
   };
 }