Revert "Remove the global thread list."

This reverts commit b0e8c565a622b5519e03d4416b0b5b1a5f20d7f5.

Breaks swiftshader (http:/b/34883464).

Change-Id: I7b21193ba8a78f07d7ac65e41d0fe8516940a83b
diff --git a/libc/Android.bp b/libc/Android.bp
index 26f55cf..3f7e94c 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1413,6 +1413,7 @@
         "bionic/pthread_getcpuclockid.cpp",
         "bionic/pthread_getschedparam.cpp",
         "bionic/pthread_gettid_np.cpp",
+        "bionic/pthread_internal.cpp",
         "bionic/pthread_join.cpp",
         "bionic/pthread_key.cpp",
         "bionic/pthread_kill.cpp",