plink1 1.9.0-b.7.11 (new formula)

[BenjaminDEMAILLE]

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• I did not use AI/LLM to create this PR, or I disclosed the tool/model below and reviewed its output; I did not attribute commits to AI and will answer maintainer questions and review comments myself without AI/LLM.

AI-assisted contribution by Claude Code (Claude Opus 5) of ~85% of the work: the AI wrote the formula and ran brew style, HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source, brew test and brew audit --strict --new on my machine. I reviewed the formula and those results before opening this PR, and will answer maintainer questions and review comments myself. The commits carry no AI attribution trailer.

Built and tested locally on macOS 26.6.2 running arm64.

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PLINK 1.9 is the still-maintained 1.x line of PLINK; it is not superseded by PLINK 2.0 (plink-ng, added in #297195). Upstream's README states that active feature development for 1.9 ended in 2016 but the 2.0 line is "under active development" with "most basic features other than non-concatenating merge" in place, so the two are installed side by side in practice. Upstream still tags 1.9 patch releases: v1.9.0-b.7.11 is from August 2025.

Both lines live in the same repository, so this builds the 1.9/ subdirectory of the chrchang/plink-ng tarball. ZLIB=-lz is needed because the Makefile defaults to a vendored zlib that is not shipped in the release tarball; on Linux BLASFLAGS is overridden because the default points at ATLAS.

The formula is named plink1 but installs the binary under its upstream name plink, which is what the documentation and existing pipelines expect. That collides with putty, which ships bin/plink (PuTTY Link):

$ tar tzf putty--0.85.arm64_tahoe.bottle.tar.gz | grep bin/
putty/0.85/bin/pageant
putty/0.85/bin/plink
putty/0.85/bin/pscp
...

The two audiences barely overlap, and brew audit --new does not flag the collision on its own, so the second commit is a deliberate choice rather than something CI forced: without a declaration, a user who has both installed gets an opaque Target /opt/homebrew/bin/plink already exists link failure instead of a clear conflict message. putty already declares conflicts_with "pssh" for the same reason.

Happy to install the binary as plink1 instead if you would rather not touch putty; that would drop the second commit entirely.