[core] Fix performance-noexcept-move-constructor in header files

As reported by clang-tidy-8.

include/mbgl/style/conversion_impl.hpp

@@ -102,7 +102,7 @@ public:
         new (static_cast<void*>(&storage)) std::decay_t<T>(std::forward<T>(value));
     }
 
-    Convertible(Convertible&& v) : vtable(v.vtable) {
+    Convertible(Convertible&& v) noexcept : vtable(v.vtable) {
         // NOLINTNEXTLINE(performance-move-const-arg)
         vtable->move(std::move(v.storage), storage);
     }
@@ -111,7 +111,7 @@ public:
         vtable->destroy(storage);
     }
 
-    Convertible& operator=(Convertible&& v) {
+    Convertible& operator=(Convertible&& v) noexcept {
         if (this != &v) {
             vtable->destroy(storage);
             vtable = v.vtable;

include/mbgl/util/image.hpp

@@ -34,13 +34,9 @@ public:
 
     Image(Size size_, std::unique_ptr<uint8_t[]> data_) : size(size_), data(std::move(data_)) {}
 
-    Image(Image&& o)
-        : size(o.size),
-          data(std::move(o.data)) {
-        o.size.width = o.size.height = 0;
-    }
+    Image(Image&& o) noexcept : size(o.size), data(std::move(o.data)) { o.size.width = o.size.height = 0; }
 
-    Image& operator=(Image&& o) {
+    Image& operator=(Image&& o) noexcept {
         size = o.size;
         data = std::move(o.data);
         o.size.width = o.size.height = 0;

include/mbgl/util/immutable.hpp

@@ -21,8 +21,8 @@ namespace mbgl {
 template <class T>
 class Mutable {
 public:
-    Mutable(Mutable&&) = default;
-    Mutable& operator=(Mutable&&) = default;
+    Mutable(Mutable&&) noexcept = default;
+    Mutable& operator=(Mutable&&) noexcept = default;
 
     Mutable(const Mutable&) = delete;
     Mutable& operator=(const Mutable&) = delete;
@@ -74,7 +74,7 @@ public:
     Immutable(Immutable<S> s)
         : ptr(std::move(s.ptr)) {}
 
-    Immutable(Immutable&&) = default;
+    Immutable(Immutable&&) noexcept = default;
     Immutable(const Immutable&) = default;
 
     template <class S>
@@ -83,7 +83,7 @@ public:
         return *this;
     }
 
-    Immutable& operator=(Immutable&&) = default;
+    Immutable& operator=(Immutable&&) noexcept = default;
     Immutable& operator=(const Immutable&) = default;
 
     const T* get() const { return ptr.get(); }

src/mbgl/gfx/debug_group.hpp

@@ -10,9 +10,7 @@ public:
         scope->pushDebugGroup(name);
     }
 
-    DebugGroup(DebugGroup&& rhs) : scope(rhs.scope) {
-        rhs.scope = nullptr;
-    }
+    DebugGroup(DebugGroup&& rhs) noexcept : scope(rhs.scope) { rhs.scope = nullptr; }
 
     ~DebugGroup() {
         if (scope) {

src/mbgl/programs/segment.hpp

@@ -22,6 +22,11 @@ public:
           indexLength(indexLength_),
           sortKey(sortKey_) {}
 
+    // FIXME: clang-tidy-8 still complains here and clang-cl
+    // on Windows gives the error: "exception specification of
+    // explicitly defaulted move constructor does not match
+    // the calculated one" when marking this 'noexcept'.
+    // NOLINTNEXTLINE(performance-noexcept-move-constructor)
     Segment(Segment&&) = default;
 
     const std::size_t vertexOffset;

src/mbgl/renderer/paint_property_binder.hpp

@@ -619,7 +619,7 @@ public:
         (void)z; // Workaround for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56958
     }
 
-    PaintPropertyBinders(PaintPropertyBinders&&) = default;
+    PaintPropertyBinders(PaintPropertyBinders&&) noexcept = default;
     PaintPropertyBinders(const PaintPropertyBinders&) = delete;
 
     void populateVertexVectors(const GeometryTileFeature& feature,

src/mbgl/util/tile_cover_impl.hpp

@@ -33,7 +33,7 @@ struct Bound {
         currentPoint = rhs.currentPoint;
         winding = rhs.winding;
     }
-    Bound& operator=(Bound&& rhs) {
+    Bound& operator=(Bound&& rhs) noexcept {
         points = std::move(rhs.points);
         currentPoint = rhs.currentPoint;
         winding = rhs.winding;