Fix compile error of the GCC with IndexLandmark braces initializer.

GCC compiler raise an error when it try to compile braces initializer of IndexLandmark
struct. This commit add explicit definition of intializers for this struct.

include/eos/core/Landmark.hpp

@@ -46,6 +46,11 @@ struct Landmark
 template <class LandmarkType>
 struct IndexedLandmark : Landmark<LandmarkType>
 {
+    IndexedLandmark(const Landmark<LandmarkType>& landmark, int model_index)
+        : Landmark<LandmarkType>(landmark), model_index(model_index) {}
+    IndexedLandmark(const std::string& name, const LandmarkType& coordinates, int model_index)
+        : Landmark<LandmarkType>{name, coordinates}, model_index(model_index) {}
+
     int model_index; ///< Index of landmark in mesh
 };
 

include/eos/core/LandmarkMapper.hpp

@@ -168,8 +168,7 @@ class LandmarkMapper
                 vertex_idx = std::stoi(converted_name.value());
             }
 
-            IndexedLandmark<LandmarkType> indexed_landmark{landmark.name, landmark.coordinates, vertex_idx};
-            indexed_landmarks.emplace_back(std::move(indexed_landmark));
+            indexed_landmarks.emplace_back(landmark, vertex_idx);
         }
         return indexed_landmarks;
     }

include/eos/fitting/ceres_nonlinear.hpp

@@ -680,11 +680,7 @@ class ModelFitter
         auto contour_landmarks = core::IndexedLandmarkCollection<LandmarkType>();
         for (int i = 0; i < image_points_contour.size(); ++i)
         {
-            core::IndexedLandmark<LandmarkType> landmark;
-            landmark.coordinates = image_points_contour[i];
-            landmark.model_index = vertex_indices_contour[i];
-
-            contour_landmarks.emplace_back(std::move(landmark));
+            contour_landmarks.emplace_back("", image_points_contour[i], vertex_indices_contour[i]);
         }
 
         return contour_landmarks;