Add cross compile parameterization for the java binding

bindings/java/Makefile

@@ -2,11 +2,14 @@ INCLUDE_DIRS = ../../src ../../blst/bindings
 
 LIBRARY_FOLDER=src/main/resources/ethereum/ckzg4844/lib
 
+CC_FLAGS=
+
 ifeq ($(OS),Windows_NT)
 	CLANG_EXECUTABLE=clang
 	GRADLE_COMMAND=gradlew
 	CLANG_FLAGS=-shared
 	JNI_INCLUDE_FOLDER=win32
+	OS_ARCH=amd64
 	LIBRARY_RESOURCE=ckzg4844jni.dll
 else
 	CLANG_EXECUTABLE=clang
@@ -15,6 +18,7 @@ else
 	ifeq ($(UNAME_S),Linux)
 		CLANG_FLAGS=-fPIC -shared
 		JNI_INCLUDE_FOLDER=linux
+		OS_ARCH=amd64
 		LIBRARY_RESOURCE=libckzg4844jni.so
 	endif
 	ifeq ($(UNAME_S),Darwin)
@@ -23,6 +27,7 @@ else
 		endif
 		CLANG_FLAGS=-dynamiclib
 		JNI_INCLUDE_FOLDER=darwin
+		OS_ARCH=x86_64
 		LIBRARY_RESOURCE=libckzg4844jni.dylib
 	endif
 endif
@@ -34,8 +39,8 @@ endif
 all: build test
 
 build:
-	mkdir -p ${LIBRARY_FOLDER}
-	${CLANG_EXECUTABLE} ${CLANG_FLAGS} -O -Wall ${addprefix -I,${INCLUDE_DIRS}} -I"${JAVA_HOME}/include" -I"${JAVA_HOME}/include/${JNI_INCLUDE_FOLDER}" -o ${LIBRARY_FOLDER}/${LIBRARY_RESOURCE} c_kzg_4844_jni.c c_kzg_4844.o ../../lib/libblst.a
+	mkdir -p ${LIBRARY_FOLDER}/${OS_ARCH}
+	${CLANG_EXECUTABLE} ${CC_FLAGS} ${CLANG_FLAGS} -O -Wall ${addprefix -I,${INCLUDE_DIRS}} -I"${JAVA_HOME}/include" -I"${JAVA_HOME}/include/${JNI_INCLUDE_FOLDER}" -o ${LIBRARY_FOLDER}/${OS_ARCH}/${LIBRARY_RESOURCE} c_kzg_4844_jni.c c_kzg_4844.o ../../lib/libblst.a
 
 test:
 	${GRADLE_COMMAND} clean test

bindings/java/src/main/java/ethereum/ckzg4844/CKzg4844JNI.java

@@ -13,7 +13,7 @@ public class CKzg4844JNI {
 
   static {
     InputStream libraryResource = CKzg4844JNI.class.getResourceAsStream(
-        "lib/" + PLATFORM_NATIVE_LIBRARY_NAME);
+        "lib/" + System.getProperty("os.arch") + "/" + PLATFORM_NATIVE_LIBRARY_NAME);
     if (libraryResource == null) {
       try {
         System.loadLibrary(LIBRARY_NAME);