libpdx: Add support for more event bits.

- Add generic abstraction for multiple event bits with an implementation-
  defined mechanism to deliver the bits.
- Update ServiceFS backend to pass through event bits.
- Implement EPOLLIN, EPOLLPRI, and EPOLLHUP event bit for UDS backed.

Bug: 34466748
Test: Build/flash system; observe stable operation.

Change-Id: I86afb5645b72ec69c095734c7891a690432150a3
diff --git a/libs/vr/libpdx_uds/Android.bp b/libs/vr/libpdx_uds/Android.bp
index 9c4a3b0..09eeaa0 100644
--- a/libs/vr/libpdx_uds/Android.bp
+++ b/libs/vr/libpdx_uds/Android.bp
@@ -5,10 +5,13 @@
         "-Wall",
         "-Wextra",
         "-Werror",
+        "-DLOG_TAG=\"libpdx_uds\"",
+        "-DTRACE=0",
     ],
     export_include_dirs: ["private"],
     local_include_dirs: ["private"],
     srcs: [
+        "channel_event_set.cpp",
         "channel_manager.cpp",
         "client_channel_factory.cpp",
         "client_channel.cpp",