[tidy] Check modernize-use-default

Ref: http://clang.llvm.org/extra/clang-tidy/checks/modernize-use-default.html

src/mbgl/geometry/glyph_atlas.cpp

@@ -19,8 +19,7 @@ GlyphAtlas::GlyphAtlas(uint16_t width_, uint16_t height_)
       dirty(true) {
 }
 
-GlyphAtlas::~GlyphAtlas() {
-}
+GlyphAtlas::~GlyphAtlas() = default;
 
 void GlyphAtlas::addGlyphs(uintptr_t tileUID,
                            const std::u32string& text,

src/mbgl/geometry/line_atlas.cpp

@@ -18,8 +18,7 @@ LineAtlas::LineAtlas(GLsizei w, GLsizei h)
       dirty(true) {
 }
 
-LineAtlas::~LineAtlas() {
-}
+LineAtlas::~LineAtlas() = default;
 
 LinePatternPos LineAtlas::getDashPosition(const std::vector<float> &dasharray, bool round, gl::ObjectStore& store) {
     size_t key = round ? std::numeric_limits<size_t>::min() : std::numeric_limits<size_t>::max();

src/mbgl/geometry/vao.cpp

@@ -13,8 +13,7 @@ void VertexArrayObject::Unbind() {
 VertexArrayObject::VertexArrayObject() {
 }
 
-VertexArrayObject::~VertexArrayObject() {
-}
+VertexArrayObject::~VertexArrayObject() = default;
 
 void VertexArrayObject::bindVertexArrayObject(gl::ObjectStore& store) {
     if (!gl::GenVertexArrays || !gl::BindVertexArray) {

src/mbgl/gl/texture_pool.cpp

@@ -64,8 +64,7 @@ void TextureReleaser::operator()(GLuint id) const {
 TexturePool::TexturePool() : impl(std::make_unique<Impl>()) {
 }
 
-TexturePool::~TexturePool() {
-}
+TexturePool::~TexturePool() = default;
 
 PooledTexture TexturePool::acquireTexture(gl::ObjectStore& store) {
     return PooledTexture { impl->acquireTexture(store) , { this } };

src/mbgl/renderer/fill_bucket.cpp

@@ -33,8 +33,7 @@ struct GeometryTooLongException : std::exception {};
 FillBucket::FillBucket() {
 }
 
-FillBucket::~FillBucket() {
-}
+FillBucket::~FillBucket() = default;
 
 void FillBucket::addGeometry(const GeometryCollection& geometry) {
     for (auto& polygon : classifyRings(geometry)) {