+/** Extend an allocated block of memory.
+ * @param[in] ptr Pointer to currently allocated block of memory (may be NULL).
+ * @param[in] size Minimum number of bytes for new block.
+ * @param[in] file File name of allocating function.
+ * @param[in] line Line number of allocating function.
+ * @return Pointer to the extended block of memory.
+ */