Fix cURL's WRITEFUNCTION undefined behavior leading to segfault

[redox]

This ensures we rely on the right CURLOPT_WRITEFUNCTION depending on whether we write to a string or to a file.

* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
  * frame #0: 0x000000010180bc04 libclang_rt.asan_osx_dynamic.dylib`__sanitizer_internal_memmove + 132
    frame #1: 0x000000010183da70 libclang_rt.asan_osx_dynamic.dylib`wrap_memcpy + 148
    frame #2: 0x0000000193c34208 libc++.1.dylib`std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>::append(char const*, unsigned long) + 144
    frame #3: 0x0000000122c24cac libduckdb.1.4.dylib`duckdb::netquack::WriteCallback(contents=0x0000629009808229, size=1, nmemb=1360, userp=0x0000000201ca69d8) at utils.cpp:87:37
    frame #4: 0x00000001ad832298 libcurl.4.dylib`cw_out_ptr_flush + 184
    frame #5: 0x00000001ad831f5c libcurl.4.dylib`cw_out_do_write + 168
    frame #6: 0x00000001ad831d64 libcurl.4.dylib`cw_out_write + 84
    frame #7: 0x00000001ad809ed8 libcurl.4.dylib`cw_download_write + 524
    frame #8: 0x00000001ad8195e4 libcurl.4.dylib`Curl_xfer_write_resp + 68
    frame #9: 0x00000001ad7f1004 libcurl.4.dylib`on_data_chunk_recv + 108
    frame #10: 0x00000001a215b800 libapple_nghttp2.dylib`nghttp2_session_mem_recv2 + 8316
    frame #11: 0x00000001ad7f1dc4 libcurl.4.dylib`h2_process_pending_input + 88
    frame #12: 0x00000001ad7f012c libcurl.4.dylib`h2_progress_ingress + 360
    frame #13: 0x00000001ad7eeffc libcurl.4.dylib`cf_h2_recv + 192
    frame #14: 0x00000001ad7cc3b0 libcurl.4.dylib`Curl_conn_recv + 48
    frame #15: 0x00000001ad8185c0 libcurl.4.dylib`Curl_readwrite + 448
    frame #16: 0x00000001ad8016bc libcurl.4.dylib`multi_runsingle + 1884
    frame #17: 0x00000001ad800eb4 libcurl.4.dylib`curl_multi_perform + 204
    frame #18: 0x00000001ad7db1b0 libcurl.4.dylib`curl_easy_perform + 272
    frame #19: 0x0000000122c0b338 libduckdb.1.4.dylib`duckdb::netquack::LoadTrancoList(db=0x000061b000004d98, force=true) at get_tranco.cpp:95:23

[hatamiarash7]

In the code, since we already have:

curl_easy_setopt(curl, CURLOPT_WRITEDATA, file);

And we haven’t set a custom write function; libcurl is already using that default fwrite-based behavior.
So adding CURLOPT_WRITEFUNCTION, NULL is redundant, and it doesn’t change anything unless we want to make it explicit.

---

If you create this PR to solve the problem stated in this comment, I must say that it is not necessary. The problem here was that you had not updated the submodules to the latest version, v1.4.0, in your PR; as a result, the ExtensionLoader was not recognized (you can check here).

[redox]

Ah great to know, I wasn't entirely sure! Might still be worth adding a update_tranco test

[redox]

I'll reopen this with an up-to-date main target - but I still reproduce the segfault

[redox]

OK, I think I understand now. I'll propose a nicer patch

[redox]

@hatamiarash7 Let me know how this patch looks to you - not sure I get how it was working before 😅