Build libnativemultinetwork_jni with C++

Test: atest MultinetworkApiTest
Change-Id: If34a89cf00aa06590d947696fc647fc26aa019e8
diff --git a/tests/cts/net/jni/Android.mk b/tests/cts/net/jni/Android.mk
index 727a44d..ccb1278 100644
--- a/tests/cts/net/jni/Android.mk
+++ b/tests/cts/net/jni/Android.mk
@@ -36,7 +36,7 @@
 LOCAL_MODULE := libnativemultinetwork_jni
 # Don't include this package in any configuration by default.
 LOCAL_MODULE_TAGS := optional
-LOCAL_SRC_FILES := NativeMultinetworkJni.c
+LOCAL_SRC_FILES := NativeMultinetworkJni.cpp
 LOCAL_CFLAGS := -Wall -Werror -Wno-format
 LOCAL_C_INCLUDES := $(JNI_H_INCLUDE)
 LOCAL_SHARED_LIBRARIES := libandroid libnativehelper_compat_libc++ liblog
diff --git a/tests/cts/net/jni/NativeMultinetworkJni.c b/tests/cts/net/jni/NativeMultinetworkJni.cpp
similarity index 94%
rename from tests/cts/net/jni/NativeMultinetworkJni.c
rename to tests/cts/net/jni/NativeMultinetworkJni.cpp
index 2fa5291..ab486e3 100644
--- a/tests/cts/net/jni/NativeMultinetworkJni.c
+++ b/tests/cts/net/jni/NativeMultinetworkJni.cpp
@@ -30,15 +30,11 @@
 #include <sys/time.h>
 #include <android/multinetwork.h>
 
-#define UNUSED(X) ((void) (X))
-
 static const char kHostname[] = "connectivitycheck.android.com";
 
-
+extern "C"
 JNIEXPORT jint Java_android_net_cts_MultinetworkApiTest_runGetaddrinfoCheck(
-        JNIEnv* env, jclass class, jlong nethandle) {
-    UNUSED(env);
-    UNUSED(class);
+        JNIEnv*, jclass, jlong nethandle) {
     net_handle_t handle = (net_handle_t) nethandle;
     struct addrinfo *res = NULL;
 
@@ -52,10 +48,9 @@
     return rval == 0 ? 0 : -saved_errno;
 }
 
+extern "C"
 JNIEXPORT jint Java_android_net_cts_MultinetworkApiTest_runSetprocnetwork(
-        JNIEnv* env, jclass class, jlong nethandle) {
-    UNUSED(env);
-    UNUSED(class);
+        JNIEnv*, jclass, jlong nethandle) {
     net_handle_t handle = (net_handle_t) nethandle;
 
     errno = 0;
@@ -66,10 +61,9 @@
     return rval == 0 ? 0 : -saved_errno;
 }
 
+extern "C"
 JNIEXPORT jint Java_android_net_cts_MultinetworkApiTest_runSetsocknetwork(
-        JNIEnv* env, jclass class, jlong nethandle) {
-    UNUSED(env);
-    UNUSED(class);
+        JNIEnv*, jclass, jlong nethandle) {
     net_handle_t handle = (net_handle_t) nethandle;
 
     errno = 0;
@@ -112,10 +106,9 @@
     strlcpy(dst, buf, size);
 }
 
+extern "C"
 JNIEXPORT jint Java_android_net_cts_MultinetworkApiTest_runDatagramCheck(
-        JNIEnv* env, jclass class, jlong nethandle) {
-    UNUSED(env);
-    UNUSED(class);
+        JNIEnv*, jclass, jlong nethandle) {
     const struct addrinfo kHints = {
         .ai_flags = AI_ADDRCONFIG,
         .ai_family = AF_UNSPEC,