added echo command for arch

Signed-off-by: Georgi Georgiev <georgi.getz@outlook.com>

Makefile

@@ -73,8 +73,10 @@ build-headers:
 	"./gradlew" --info generateJniHeaders
 
 # Run the tests.
-test: build-headers build-rust test-rust build-java
+test: echo-arch build-headers build-rust test-rust build-java
 
+echo arch:
+    echo $(build_arch)-$(build_os)
 # Run the Rust tests.
 test-rust: test-rust-$(build_arch)-$(build_os)