Remove private header include

Change-Id: I62d3e331ba2e055848904d2edbdc29eacbf5e85f
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/android.googlesource.com/platform/system/libfmq/+/914192
Reviewed-by: Adam Barth <abarth@google.com>
diff --git a/tests/fmq_unit_tests.cpp b/tests/fmq_unit_tests.cpp
index 03db6ec..7cd0d33 100644
--- a/tests/fmq_unit_tests.cpp
+++ b/tests/fmq_unit_tests.cpp
@@ -20,7 +20,6 @@
 #include <fmq/ConvertMQDescriptors.h>
 #include <fmq/EventFlag.h>
 #include <fmq/MessageQueue.h>
-#include <gtest/gtest-death-test.h>
 #include <gtest/gtest.h>
 #include <sys/resource.h>
 #include <atomic>