(L) Prelim RFR: 8132510: Replace ThreadLocalStorage with compiler/language-based thread-local variables

[David Holmes]

Hi Thomas,

Okay here's the next revision:

http://cr.openjdk.java.net/~dholmes/8132510/webrev.v5/

I've reinstated a basic ThreadLocalStorage class which will only need 
two implementations: a POSIX one, and a Windows one (still TBD). This 
class is always initialized and ThreadLocalStorage::thread() is used 
from the signal handlers (as today).

For platforms that don't have __thread support they can define 
USE_LIBRARY_BASED_TLS_ONLY at build time to only use the 
ThreadLocalStorage implementation.

Obviously still need to get some performance numbers.

I'd appreciate it if you could retest AIX, though as all platforms 
currently use pthread_get/setspecific I'm confident there will be no 
platform issues.

Thanks,
David