[Yizhou Tong (tsurumi-yizhou)]

Updates llhttp to 9.4.3.

Releases since the current 9.3.1:

• 9.4.0: https://github.com/nodejs/llhttp/releases/tag/release/v9.4.0 — modern
  CMake config/version files, support for building both static and shared, and
  relaxed header value parsing.
• 9.4.2: https://github.com/nodejs/llhttp/releases/tag/release/v9.4.2 — require
  CRLF in the status line; correctly handle a tab after a Connection: close
  header value.
• 9.4.3: https://github.com/nodejs/llhttp/releases/tag/release/v9.4.3 — do not
  allow an empty Transfer-Encoding.

The 9.4.2 and 9.4.3 changes are request-smuggling / response-splitting
hardening: 9.3.1 accepts messages that these releases reject. HTTP libraries
that parse untrusted traffic should not stay on 9.3.1.

The existing static-only portfile is unchanged apart from the SHA512;
LLHTTP_BUILD_SHARED_LIBS / LLHTTP_BUILD_STATIC_LIBS are still the options
9.4.3 exposes, and vcpkg x-add-version llhttp --overwrite-version regenerated
the version record.

Testing: vcpkg install llhttp:x64-linux from this branch succeeds and
installs libllhttp.a with the llhttp::llhttp_static CMake target; a C++23
consumer (httpant) builds and passes its HTTP/1.1 conformance and framing
tests against it.

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