proactively track TLS reservations

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on August 03, 2011 17:59:29_

this issue covers the FIXME here since the performance is showing up on
chrome, esp with -no_check_uninitialized where an unaddr costs a full
fault (which on Windows incurs a thread_initexit_lock acquisition):

```
/* For TLS, rather than proactively track sets and unsets, we check
* on fault for whether set and we never mark as addressable.
* FIXME: for performance we should proactively track so we can mark
* as addressable. Should just watch the API and let people who
* bypass to set the bits themselves deal w/ the false positives instead
* of adding checks to all writes to catch tls bitmask writes.
*/
```

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=537_