Update `databases/iowow' to version 1.3.9

Summary of the most important changes since version 1.2.14:

• Removed ability to manage sorted arrays as key values due to performance issues; replaced with two-part compound keys + Added support of variable-length encoded integer keys + Added atomic in-place integer key value increments + Added new utility functions and flags
• Fixed incorrect key handling in iwkv_del()
• Fixed iwkv_cursor_copy_key() which was not aware of the compound keys mode
• Fixed iwkv_puth() was called with incorrect previous value
• Fixed deadlocks in iwkv_del() by not escalating exclusive lock on the storage
• Fixed iwxstr_new2() with zero size argument caused illegal memory write
• Fixed memory leak in iwkv_cursor_open() on error
• Fixed high CPU usage in WAL mode

Requested by: upstream