cpp-httplib: link Apple frameworks for CFHost resolver, add with_non_blocking_getaddrinfo option

[andiwand]

Summary

Changes to recipe: cpp-httplib/all (applies to 0.28.0 and 0.47.0)

Motivation

On Apple platforms the recipe unconditionally defines CPPHTTPLIB_USE_NON_BLOCKING_GETADDRINFO, which compiles the CFHost-based asynchronous DNS resolver in getaddrinfo_with_timeout(). That resolver references CoreFoundation/CFNetwork symbols (CFHostCreateWithName, CFRunLoopGetCurrent, CFRelease, ...), but the frameworks were only linked in the narrow macOS _tls_enabled and use_macos_keychain_certs case — and never for iOS/tvOS/watchOS at all.

As a result, any consumer that builds without the macOS keychain-certs configuration, or that targets a non-macOS Apple platform, fails to link:

Undefined symbols for architecture arm64:
  "_CFHostCreateWithName", referenced from:
      httplib::detail::getaddrinfo_with_timeout(...) in ...
  "_CFRunLoopGetCurrent", referenced from:
      ...
ld: symbol(s) not found for architecture arm64

The existing test_package only constructs a httplib::Request, so it never references the resolver and did not catch this.

Details

1. Fix the Apple framework linking. Link CoreFoundation + CFNetwork on every Apple OS (via is_apple_os) whenever the non-blocking getaddrinfo path is compiled in; Security stays scoped to the macOS keychain-certs case. test_package now references the client request path — guarded so no network request is made at runtime — so the resolver symbol is pulled in at link time and the regression is covered.

2. Add a with_non_blocking_getaddrinfo option (default True). That define is what pulls in the platform resolver dependencies: CoreFoundation/CFNetwork on Apple and libanl on glibc. Without it, getaddrinfo_with_timeout() falls back to a plain blocking getaddrinfo() and ignores the resolution timeout, so it is a robustness feature rather than a functional requirement. Defaulting to True preserves current behavior; consumers that do not need DNS-phase timeouts can set it to False to drop the define and the extra link dependencies.

Tested locally with Conan on macOS/arm64 (apple-clang) for cpp-httplib/0.28.0 with: default options, use_macos_keychain_certs=False (the previously failing configuration), and with_non_blocking_getaddrinfo=False.

---

• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• If this is a bug fix, please link related issue or provide bug details
• Tested locally with at least one configuration using a recent version of Conan