Improve full inertia user API.

PiperOrigin-RevId: 627399310
Change-Id: Ie2bdc6778e80b2b8127b52c73a3cc4b4755d8e0a

src/user/user_model.cc

@@ -2861,7 +2861,7 @@ void mjCModel::FuseStatic(void) {
 
         // compute principal axes of inertia
         mjuu_copyvec(par->fullinertia, toti, 6);
-        const char* err1 = par->FullInertia(par->iquat, par->inertia);
+        const char* err1 = FullInertia(par->iquat, par->inertia, par->fullinertia);
         if (err1) {
           throw mjCError(NULL, "error '%s' in fusing static body inertias", err1);
         }