Add missing serialization to FILE for vector of pointers (issue #3925)

It is required for mftraining which otherwise writes a wrong shapetable.

Signed-off-by: Stefan Weil <sw@weilnetz.de>

src/ccutil/helpers.h

@@ -31,6 +31,8 @@
 #include <string>
 #include <vector>
 
+#include "serialis.h"
+
 namespace tesseract {
 
 template <class T>
@@ -242,6 +244,19 @@ bool Serialize(FILE *fp, const std::vector<T> &data) {
         return false;
       }
     }
+  } else if constexpr (std::is_pointer<T>::value) {
+    // Serialize pointers.
+    for (auto &item : data) {
+      uint8_t non_null = (item != nullptr);
+      if (!Serialize(fp, &non_null)) {
+        return false;
+      }
+      if (non_null) {
+        if (!item->Serialize(fp)) {
+          return false;
+        }
+      }
+    }
   } else if (size > 0) {
     if (fwrite(&data[0], sizeof(T), size, fp) != size) {
       return false;