AmigaOS: fix build fallouts, re-add to CI

Fix build issues:
- src: adjust `toolx_ftruncate()`.
- libtests/cli_ftp_upload: make `struct timeval` initialization portable.
- libtests/lib1960: do unconst in local `inet_pton()` macro.
- tests/server/dnsd: make it stub instead of failing the build.
- tests/server: make them link AmiSSL for `SocketBase`.

Also:
- bump AmiSSL to the latest release.
- add download hash checks and toolchain cache.
- sync restored code with local updates made since last year.

It takes 30 seconds per job, 1 minute in total.

Thanks-to: Bebbo
Thanks-to: Darren Banfi
Ref: https://github.com/curl/curl/pull/21989#issuecomment-4691380623
Follow-up to 7a14898264 #17486

Closes #21993

CMakeLists.txt

@@ -681,6 +681,7 @@ elseif(AMIGA)
     set(OPENSSL_CRYPTO_LIBRARY "${AMISSL_AUTO_LIBRARY}")
     set(CURL_USE_OPENSSL ON)
     set(CURL_CA_FALLBACK ON CACHE BOOL "")
+    list(PREPEND CURL_NETWORK_AND_TIME_LIBS "${AMISSL_STUBS_LIBRARY}" "${AMISSL_AUTO_LIBRARY}")
   endif()
 elseif(NOT WIN32 AND NOT APPLE)
   check_library_exists("socket" "connect" "" HAVE_LIBSOCKET)