nativebridge: Add PreZygoteFork callback

It's required to clean-up the emulated enviroment (e.g. close file
descriptors) after emulated execution in doPreload() in app-zygote.

Test: NativeBridge6PreZygoteFork_test
Test: CtsSeccompHostTestCases
android.seccomp.cts.SeccompHostJUnit4DeviceTest
testAppZygoteSyscalls
both for Q.sdk_gphone_x86_arm.armeabi-v7a
Bug: 146904103

Change-Id: Id192a1647c2f405570bf196daf65b3f2a9faca42
diff --git a/libnativebridge/tests/NativeBridge6PreZygoteFork_lib.h b/libnativebridge/tests/NativeBridge6PreZygoteFork_lib.h
new file mode 100644
index 0000000..bcbf0d3
--- /dev/null
+++ b/libnativebridge/tests/NativeBridge6PreZygoteFork_lib.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+#ifndef ART_LIBNATIVEBRIDGE_TESTS_NATIVEBRIDGE6PREZYGOTEFORK_LIB_H_
+#define ART_LIBNATIVEBRIDGE_TESTS_NATIVEBRIDGE6PREZYGOTEFORK_LIB_H_
+
+namespace android {
+
+bool IsPreZygoteForkDone();
+void SetPreZygoteForkDone();
+
+}  // namespace android
+
+#endif  // ART_LIBNATIVEBRIDGE_TESTS_NATIVEBRIDGE6PREZYGOTEFORK_LIB_H_