Build libzstd from source for macOS release wheels

Summary:
Fixes a `delocate.libsana.DelocationError` in the macOS leg of the release
workflow. After the prior fix (pinning cibuildwheel to v3.4.1 and installing
libzstd via `brew install zstd`), the macOS run got past the build step but
failed at `delocate-wheel` with:

    Library dependencies do not satisfy target MacOS version 11.0:
    tintype/.dylibs/libzstd.1.5.7.dylib has a minimum target of 15.0

Root cause: `macos-latest` runners now run macOS 15 (Sequoia), and Homebrew
bottles on those runners are built targeting the runner OS. But cibuildwheel
tags arm64 wheels with a minimum macOS of 11.0 by default, and delocate
refuses to bundle a dylib whose LC_VERSION_MIN is higher than the wheel's.

Fix: replace `brew install zstd` in `CIBW_BEFORE_ALL_MACOS` with a CMake
source build of libzstd 1.5.6 producing a universal2 (arm64 + x86_64) dylib
explicitly targeting macOS 11.0, installed to `/usr/local`.
`setup.py`'s `find_zstd()` searches `/usr`, `/usr/local`, `/opt/homebrew`
in that order, so installing to `/usr/local` takes precedence over any
leftover Homebrew install. The `brew uninstall` before the build is
defensive cleanup.

Also sets `CIBW_ENVIRONMENT_MACOS: MACOSX_DEPLOYMENT_TARGET=11.0`. Without
this, cibuildwheel would default the x86_64 leg to 10.13 — which is lower
than the vendored libzstd's 11.0 target and would trigger the same
DelocationError in the opposite direction.

Trade-off: wheels now require macOS 11.0 (Big Sur, Nov 2020) or newer on
both architectures. Previously arm64 required 11.0 (unchanged) and x86_64
defaulted to 10.13. This is fine in practice — macOS 11 is >5 years old.

Reviewed By: aperez

Differential Revision: D103472663

fbshipit-source-id: 8d3d456cddbbacf4b4a45213e5b353a97c80df97

Author: pdepetro

.github/workflows/release.yml

@@ -62,10 +62,33 @@ jobs:
           # Install libzstd inside the manylinux container (mirrors ci.yml's
           # `apt install libzstd-dev` but adapted for the CentOS-based image).
           CIBW_BEFORE_ALL_LINUX: "yum install -y libzstd-devel"
-          # macOS: zstd is needed at build time. brew provides it for the
-          # runner's native arch; the x86_64 cross-compile leg may need
-          # additional work if the linker can't find an Intel build.
-          CIBW_BEFORE_ALL_MACOS: "brew install zstd"
+          # macOS: the macos-latest runner (macOS 15+) ships Homebrew bottles
+          # targeting macOS 15, but cibuildwheel tags our wheel as macOS 11.
+          # delocate refuses to bundle a dylib with a higher min target than
+          # the wheel, so we build libzstd from source as a universal2 dylib
+          # targeting macOS 11.0. setup.py's find_zstd() searches
+          # /usr, /usr/local, /opt/homebrew in order, so /usr/local wins over
+          # any leftover Homebrew install.
+          CIBW_BEFORE_ALL_MACOS: |
+            brew uninstall --ignore-dependencies zstd 2>/dev/null || true
+            ZSTD_VERSION=1.5.6
+            curl -fL "https://github.com/facebook/zstd/releases/download/v${ZSTD_VERSION}/zstd-${ZSTD_VERSION}.tar.gz" | tar -xz -C /tmp
+            cmake -S "/tmp/zstd-${ZSTD_VERSION}/build/cmake" -B /tmp/zstd-build \
+              -DCMAKE_BUILD_TYPE=Release \
+              -DCMAKE_OSX_DEPLOYMENT_TARGET=11.0 \
+              -DCMAKE_OSX_ARCHITECTURES="arm64;x86_64" \
+              -DZSTD_BUILD_SHARED=ON \
+              -DZSTD_BUILD_STATIC=OFF \
+              -DZSTD_BUILD_PROGRAMS=OFF \
+              -DZSTD_BUILD_TESTS=OFF \
+              -DCMAKE_INSTALL_PREFIX=/usr/local
+            cmake --build /tmp/zstd-build --parallel
+            sudo cmake --install /tmp/zstd-build
+          # Pin both x86_64 and arm64 legs to the same minimum macOS target
+          # that our vendored libzstd was built against (otherwise the x86_64
+          # default of 10.13 would be lower than the dylib's 11.0 and delocate
+          # would fail again).
+          CIBW_ENVIRONMENT_MACOS: MACOSX_DEPLOYMENT_TARGET=11.0
 
       - name: Upload wheels artifact
         uses: actions/upload-artifact@v4