Create a timerfd JNI class

The timerfd delivers timer expiration notifications via a file
descriptor, which can be used to implement delayed callbacks.
Create a JNI class to interface with the timerfd system calls.

Bug: 366373064
Test: m
Change-Id: I0ae7a4cf618838e614b2fa4523b55a4d0e8f74e2
diff --git a/tests/unit/jni/Android.bp b/tests/unit/jni/Android.bp
index 57a157d..50971e7 100644
--- a/tests/unit/jni/Android.bp
+++ b/tests/unit/jni/Android.bp
@@ -42,6 +42,7 @@
     ],
     static_libs: [
         "libnet_utils_device_common_bpfjni",
+        "libnet_utils_device_common_timerfdjni",
         "libtcutils",
     ],
     shared_libs: [