ANDROID: Expose futex header for vendor hooks

This header is required for vendor hooks that
need to access internal futex structures and states,
such as when implementing optimization logic for
futex-related blocking.

This work is part of the effort to address SysUI
blocking call regressions observed, as tracked in
the linked bug.

Bug: 475297563
Change-Id: I31fa10ebba411834195432ffc0a321ec3e066dd5
Signed-off-by: Chung-Kai (Michael) Mei <chungkai@google.com>

BUILD.bazel

diff --git a/BUILD.bazel b/BUILD.bazel
index 4d72256..321e017 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -1933,6 +1933,7 @@
         "drivers/android/binder_internal.h",
         "drivers/android/binder_trace.h",
         "drivers/android/dbitmap.h",
+        "kernel/futex/futex.h",
         "kernel/sched/cpudeadline.h",
         "kernel/sched/cpupri.h",
         "kernel/sched/ext.h",