GH-1415: Build bundled lz4 in the macOS JNI build (#1416)

The `JNI macos-15 aarch_64` job in the RC workflow fails on `main` with
`Unexpected shared dependency found in
arrow_dataset_jni/aarch_64/libarrow_dataset_jni.dylib: liblz4`.
Homebrew's `lz4` now installs a CMake package configuration whose
`LZ4::lz4` target is the shared library. Arrow C++'s `Findlz4Alt.cmake`
uses that target as is, ignoring `ARROW_LZ4_USE_SHARED=OFF`, so on the
newer `macos-15-arm64` runner image (20261028.0489) the JNI libraries
are linked with `/opt/homebrew/lib/liblz4.1.10.0.dylib`.

This builds lz4 from source with `-Dlz4_SOURCE=BUNDLED` in
`jni_macos_build.sh`, like abseil, simdjson and uriparser. The bundled
lz4 goes into `libarrow_bundled_dependencies.a`, and the bundled ORC
build uses it too.

Not tested locally because it needs the full Arrow C++ build. The `JNI
macos-15 aarch_64` check on this PR is the verification. Jobs on the
older runner image (20260907.0337) pass even without this change, so the
check is only meaningful if it runs on the newer image.

Closes #1415.

Author: jbonofre

ci/scripts/jni_macos_build.sh

@@ -74,6 +74,7 @@ cmake \
   -B "${build_dir}/cpp" \
   --preset=ninja-release-jni-macos \
   -Dabsl_SOURCE=BUNDLED \
+  -Dlz4_SOURCE=BUNDLED \
   -Dsimdjson_SOURCE=BUNDLED \
   -Duriparser_SOURCE=BUNDLED \
   -DCMAKE_INSTALL_PREFIX="${install_dir}"