obi java agent build fails on macos

[esara]

Build fails because the native JNI build uses the Linux include path on macOS; jni_md.h lives in the platform-specific include dir (e.g. darwin on macOS). On macOS that file lives under include/darwin, so the compiler couldn’t find it.

$ cd pkg/internal/java
$ ./gradlew :loader:build

> Task :agent:buildNativeLib FAILED
clang -fPIC -O2 -Wall -Wextra -Wno-unused-parameter -I/Library/Java/JavaVirtualMachines/jdk-25.0.2.jdk/Contents/Home/include -I/Library/Java/JavaVirtualMachines/jdk-25.0.2.jdk/Contents/Home/include/linux -Ibuild/generated/jni-headers -Isrc/main/c -c src/main/c/io_opentelemetry_obi_java_jni.c -o build/io_opentelemetry_obi_java_jni.o
In file included from src/main/c/io_opentelemetry_obi_java_jni.c:6:
/Library/Java/JavaVirtualMachines/jdk-25.0.2.jdk/Contents/Home/include/jni.h:45:10: fatal error: 'jni_md.h' file not found
   45 | #include "jni_md.h"
      |          ^~~~~~~~~~
1 error generated.
make: *** [build/io_opentelemetry_obi_java_jni.o] Error 1