Make signalfd wrapper more robust

I realized afterwards it's only used in tests, but whatever.

Change-Id: I23f654a0119faefec6a3888dc7d7c8ba38cf1b4f
diff --git a/aos/ipc_lib/BUILD b/aos/ipc_lib/BUILD
index 908cb80..57adc6d 100644
--- a/aos/ipc_lib/BUILD
+++ b/aos/ipc_lib/BUILD
@@ -164,6 +164,19 @@
     ],
 )
 
+cc_test(
+    name = "signalfd_test",
+    srcs = [
+        "signalfd_test.cc",
+    ],
+    deps = [
+        ":signalfd",
+        "//aos/testing:googletest",
+        "//aos/testing:test_logging",
+        "@com_github_google_glog//:glog",
+    ],
+)
+
 cc_library(
     name = "index",
     srcs = ["index.cc"],