SuperFAISS 3.4.3

3.4.1 and 3.4.2 were SuperFAISS For Unreal Engine plugin releases; the core library goes
from 3.4.0 to 3.4.3 so the two share one version line.

Fixed

• Builds with clang-cl. CMake reports clang-cl as MSVC, so it was given only cl.exe's
  switches: kernels.cpp lacked the SSE4.1 target feature and clang-cl rejected its
  intrinsics, and CPU detection called __builtin_cpu_supports, whose __cpu_model lives
  in a compiler-rt that clang-cl does not link. clang-cl now also gets
  /clang:-ffp-contract=off (its /fp:precise contracts a*b+c into FMA, which the
  determinism contract forbids) and /clang:-msse4.2 on kernels.cpp for x64/X86, and CPU
  detection takes the CPUID path cl.exe takes. cl.exe x64/X86, GCC and Clang command lines
  are unchanged.
• CPUID detection checks the maximum basic leaf. The CPUID path (cl.exe, clang-cl) now
  confirms leaf 7 exists before reading its AVX2 bit.
• /arch:AVX2 is applied only for x64/X86 targets, not for ARM64 MSVC builds.

Changed

• The minimum MSVC version is 19.30 (Visual Studio 2022): from that version on, cl.exe's
  /fp:precise does not contract. CMake now stops with an error on an older cl.exe. The
  build-flag tables in docs/INTEGRATION.md and
  docs/DETERMINISM.md gain the clang-cl flags.