RFR: 8217348: assert(thread->is_Java_thread()) failed: just checking

[Daniil Titov]

Please review the change that fixes an intermittent issue.

The problem here is that a bitwise-AND (&) operator was used in the condition instead of a logical AND operator (&&). 
As a result pending_thread->is_thread_fully_suspended() is always evaluated regardless of the value of at_safepoint variable.

Webrev: http://cr.openjdk.java.net/~dtitov/8217348/webrev.01/
Bug: https://bugs.openjdk.java.net/browse/JDK-8217348 

Thanks!
--Daniil