Request for review (S) 7012088: jump to 0 address because of lack of memory ordering in SignatureHandler::add

[Coleen Phillimore]

Summary: Write method signature handler under lock to prevent race with 
growable array resizing

Also includes a fix to 6704010 which was broken with 
-XX:-UseFastSignatureHandlers

This change was submitted and tested by the customer.

open webrev at http://cr.openjdk.java.net/~coleenp/7012088/
bug link at http://bugs.sun.com/view_bug.do?bug_id=7012088

Thanks,
Coleen