Fix bug in finding another thread's TCB.

Change-Id: I06c86ca0c077b464fc6c9fbdf5b89889a26da5fb
diff --git a/tests/libs/Android.bp b/tests/libs/Android.bp
index ef4fddd..4b86faf 100644
--- a/tests/libs/Android.bp
+++ b/tests/libs/Android.bp
@@ -80,7 +80,7 @@
 }
 
 cc_test {
-   name: "thread_exit_cb_helper.cpp",
+   name: "thread_exit_cb_helper",
    defaults: ["bionic_testlib_defaults"],
    srcs: ["thread_exit_cb_helper.cpp"],
    cflags: ["-fno-emulated-tls"],