Make InputReader test components thread safe

This changes all assert*() methods in the following classes to enable
waiting for the assertion to be true:
- FakeInputReaderPolicy
- FakeEventHub
- FakeInputMapper
- TestInputListener

This change should make InputReader robust to being run on another
thread.

Bug: 130819454
Test: atest inputflinger_tests # on crosshatch
Change-Id: I9619109e3377eb706d71fb34d525bd3bdc4ef81a
diff --git a/services/inputflinger/tests/Android.bp b/services/inputflinger/tests/Android.bp
index c4f8626..ada2266 100644
--- a/services/inputflinger/tests/Android.bp
+++ b/services/inputflinger/tests/Android.bp
@@ -15,6 +15,7 @@
         "-Werror",
         "-Wextra",
         "-Wno-unused-parameter",
+        "-Wthread-safety",
     ],
     shared_libs: [
         "android.hardware.input.classifier@1.0",