Fix alignment error for pthread_internal_t/pthread stack.

aligned attribute can only control compiler's behavior, but we
are manually allocating pthread_internal_t. So we need to make
sure of alignment manually.

Change-Id: Iea4c46eadf10dfd15dc955c5f41cf6063cfd8536
diff --git a/libc/bionic/pthread_internal.h b/libc/bionic/pthread_internal.h
index 538e0da..13964c2 100644
--- a/libc/bionic/pthread_internal.h
+++ b/libc/bionic/pthread_internal.h
@@ -103,7 +103,7 @@
    */
 #define __BIONIC_DLERROR_BUFFER_SIZE 512
   char dlerror_buffer[__BIONIC_DLERROR_BUFFER_SIZE];
-} __attribute__((aligned(16))); // Align it as thread stack top below it should be aligned.
+};
 
 __LIBC_HIDDEN__ int __init_thread(pthread_internal_t* thread, bool add_to_thread_list);
 __LIBC_HIDDEN__ void __init_tls(pthread_internal_t* thread);