Do not hold a reference to the Style at the [Live|Vector]TileData

Layers are added and removed dynamically on the Map thread when we use shape
annotations and we are iterating style.layers on the Worker thread without
any lock.

Now when we create a [Live|Vector]TileData at the Map thread we give it
a layers list (instead of the Style) and [Live|Vector]TileData will ultimately
make a copy of this list (on the Map thread, so no concurrency with
adding shape annotations).

The copy should be relatively cheap because we are using a shared pointer
for storing the layers on the list.

src/mbgl/map/live_tile_data.cpp

@@ -10,7 +10,8 @@ using namespace mbgl;
 
 LiveTileData::LiveTileData(const TileID& id_,
                            AnnotationManager& annotationManager_,
-                           Style& style_,
+                           const std::vector<util::ptr<StyleLayer>>& layers_,
+                           Worker& workers_,
                            GlyphAtlas& glyphAtlas_,
                            GlyphStore& glyphStore_,
                            SpriteAtlas& spriteAtlas_,
@@ -18,7 +19,7 @@ LiveTileData::LiveTileData(const TileID& id_,
                            const SourceInfo& source_,
                            float angle_,
                            bool collisionDebug_)
-    : VectorTileData::VectorTileData(id_, style_, glyphAtlas_, glyphStore_,
+    : VectorTileData::VectorTileData(id_, layers_, workers_, glyphAtlas_, glyphStore_,
                                      spriteAtlas_, sprite_, source_, angle_, collisionDebug_),
       annotationManager(annotationManager_) {
     // live features are always ready
@@ -43,7 +44,7 @@ void LiveTileData::parse() {
             // Parsing creates state that is encapsulated in TileParser. While parsing,
             // the TileParser object writes results into this objects. All other state
             // is going to be discarded afterwards.
-            TileParser parser(*tile, *this, style, glyphAtlas, glyphStore, spriteAtlas, sprite);
+            TileParser parser(*tile, *this, layers, glyphAtlas, glyphStore, spriteAtlas, sprite);
             parser.parse();
         } catch (const std::exception& ex) {
             Log::Error(Event::ParseTile, "Live-parsing [%d/%d/%d] failed: %s", id.z, id.x, id.y, ex.what());