Lutok 0.6: minor modernization release

Changes in version 0.6

Released on 2024/01/04.

• Remove lingering C++-11 support. The project now requires a C++14 compliant toolchain to build.

• Fix a Doxygen warning by deleting the stack_cleaner copy/assignment operator.

• Vendor the ATF m4 files from freebsd/[email protected] ,

• m4/lua.m4: remove legacy lua-config support in favor of pkg_config.

• Fix a benign buffer overrun complaint from gcc 13.2.

• Rename --with-atf to --enable-atf.

Full Changelog: lutok-0.5...lutok-0.6