Fix #135490: Incorrect allocation size with MEM_new (naming collisions)

Resolve naming collisions for structs which could cause the wrong size
to be used allocating the `LaplacianSystem` when calculating mesh
weights from an armature.

Ref !135491

source/blender/modifiers/intern/MOD_laplaciandeform.cc

@@ -49,6 +49,9 @@ enum {
   LAPDEFORM_SYSTEM_CHANGE_NOT_VALID_GROUP,
 };
 
+/* Prevent naming collision. */
+namespace {
+
 struct LaplacianSystem {
   bool is_matrix_computed;
   bool has_solution;
@@ -87,6 +90,8 @@ struct LaplacianSystem {
   MeshElemMap *ringv_map;
 };
 
+};  // namespace
+
 static LaplacianSystem *newLaplacianSystem()
 {
   LaplacianSystem *sys = MEM_cnew<LaplacianSystem>(__func__);

source/blender/modifiers/intern/MOD_laplaciansmooth.cc

@@ -31,6 +31,9 @@
 
 #include "eigen_capi.h"
 
+/* Prevent naming collision. */
+namespace {
+
 struct LaplacianSystem {
   float *eweights = nullptr;      /* Length weights per Edge */
   float (*fweights)[3] = nullptr; /* Cotangent weights per face */
@@ -54,6 +57,8 @@ struct LaplacianSystem {
   float vert_centroid[3] = {};
 };
 
+};  // namespace
+
 static void delete_laplacian_system(LaplacianSystem *sys)
 {
   MEM_SAFE_FREE(sys->eweights);