[foosekis4j]

Problem

On x86_64, build_native_lib.sh builds the native library for Sapphire Rapids. Highway's HWY_AVX3_SPR target needs
GCC 12 or newer (third_party/highway/hwy/detect_targets.h), but the script required GCC 11. With GCC 11 the
version check passes, and the build then fails inside Highway.

The script also checks g++, while meson compiles with $CXX when it is set. So a machine with an old default
g++ and a newer compiler in CXX (for example CXX=g++-13, or gcc-toolset on RHEL) was rejected, even though
the build would have worked.

Change

• MIN_GCC_VERSION is 12 on x86_64, and unchanged (11) elsewhere.
• The compiler checked is ${CXX:-g++}, the one meson uses. Its version comes from -dumpfullversion -dumpversion
  (-dumpversion alone prints only the major version since GCC 7).

Tested

On Ubuntu 22.04 x86_64, default g++ 11.4.0:

• Without CXX: the script stops before building:

  ERROR: g++ version 11.4.0 is too old. Please upgrade to g++ 12 or newer, or set CXX to one.
  

• With CXX=g++-13: it builds libjvector-x86_64.so.

[github-actions]

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