Make the native bridge API a C API.

In order to move the library into the runtime APEX.

Test: m and boot
Bug: 119840313
Bug: 122710865
Change-Id: I4aac5954d2fb5f9e3ba92e486d69f1e76614df92
diff --git a/libnativebridge/tests/NativeBridgeApi.c b/libnativebridge/tests/NativeBridgeApi.c
new file mode 100644
index 0000000..7ab71fe
--- /dev/null
+++ b/libnativebridge/tests/NativeBridgeApi.c
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* The main purpose of this test is to ensure this C header compiles in C, so
+ * that no C++ features inadvertently leak into the C ABI. */
+#include "nativebridge/native_bridge.h"
+
+int main(int argc, char** argv) {
+  (void)argc;
+  (void)argv;
+  return 0;
+}