Avoid returning 'assets.lst' from forEachFile()

The assets.lst is intended to be converted into vfs::Visibility values by the
VFS module, not returned directly as a file.

radiant/test/vfsTest.cpp

@@ -70,4 +70,8 @@ BOOST_FIXTURE_TEST_CASE(handleAssetsLst, VFSFixture)
     BOOST_TEST(fileVis.count("darkmod/test/unit_cube.ase") == 1);
     BOOST_TEST(fileVis["darkmod/test/unit_cube.ase"] == vfs::Visibility::HIDDEN);
     BOOST_TEST(fileVis["darkmod/test/unit_cube.lwo"] == vfs::Visibility::NORMAL);
+
+    // The assets.lst should be converted into visibility information, but NOT
+    // returned as an actual file to the calling code.
+    BOOST_TEST(fileVis.count("assets.lst") == 0);
 }

radiant/vfs/Doom3FileSystem.cpp

@@ -211,6 +211,10 @@ class FileVisitor: public Archive::Visitor
             return; // already visited
         }
 
+        // Don't return assets.lst itself
+        if (subname == AssetsList::FILENAME)
+            return;
+
         // Suitable file, call the callback and add to visited file set
         vfs::Visibility vis = _assetsList ? _assetsList->getVisibility(subname)
                                           : Visibility::NORMAL;