liblinphone: fix missing vcard_grammar

Fixes #84488

pkgs/applications/networking/instant-messengers/linphone/default.nix

@@ -223,7 +223,6 @@ mkDerivation rec {
     cp linphone.desktop $out/share/applications/
     cp -r ../assets/icons $out/share/
     mkdir -p $out/share/belr/grammars
-    ln -s ${belcard}/share/belr/grammars/* $out/share/belr/grammars/
     ln -s ${liblinphone}/share/belr/grammars/* $out/share/belr/grammars/
     mkdir -p $out/share/linphone
     ln -s ${liblinphone}/share/linphone/* $out/share/linphone/

pkgs/development/libraries/liblinphone/default.nix

@@ -140,6 +140,15 @@ stdenv.mkDerivation rec {
     pkgconfig
   ];
 
+  # Some grammar files needed to be copied too from some dependencies. I suppose
+  # if one define a dependency in such a way that its share directory is found,
+  # then this copying would be unnecessary. Instead of actually copying these
+  # files, create a symlink.
+  postInstall = ''
+    mkdir -p $out/share/belr/grammars
+    ln -s ${belcard}/share/belr/grammars/* $out/share/belr/grammars/
+  '';
+
   meta = with stdenv.lib; {
     homepage = "https://www.linphone.org/technical-corner/liblinphone";
     description = "Library for SIP calls and instant messaging";