ad59322ae4
This was originally motivated by noticing that we were setting the wrong bits for the well-known tls entries. That was a harmless bug because none of the well-known tls entries has a destructor, but it's best not to leave land mines lying around. Also add some missing POSIX constants, a new test, and fix pthread_key_create's return value when we hit the limit. Change-Id: Ife26ea2f4b40865308e8410ec803b20bcc3e0ed1