Revert "Revert "More pthreads cleanup.""

This reverts commit 6f94de3ca49e4ea147b1c59e5818fa175846518f

(Doesn't try to increase the number of TLS slots; that leads to
an inability to boot. Adds more tests.)

Change-Id: Ia7d25ba3995219ed6e686463dbba80c95cc831ca
diff --git a/libc/bionic/pthread_internal.h b/libc/bionic/pthread_internal.h
index 24b420c..63071d9 100644
--- a/libc/bionic/pthread_internal.h
+++ b/libc/bionic/pthread_internal.h
@@ -62,6 +62,10 @@
 
 __LIBC_HIDDEN__ void pthread_key_clean_all(void);
 
+#define PTHREAD_ATTR_FLAG_DETACHED      0x00000001
+#define PTHREAD_ATTR_FLAG_USER_STACK    0x00000002
+
+extern __LIBC_HIDDEN__ const pthread_attr_t gDefaultPthreadAttr;
 extern pthread_internal_t* gThreadList;
 extern pthread_mutex_t gThreadListLock;