RFR(S): 8063112: Compiler diagnostic commands should have locking instead of safepoint

[Nils Eliasson]

Hi,

Please review.

Summary:
Firstly this change removes the unnecessary vm-ops from three compiler 
diagnostic commands and adds locking instead.
Secondly the Compiler.queue diagnostic command is improved with printing 
of any active compilations. I found this useful when diagnosing a rouge VM.
Thirdly, as a bonus, I also add printing of active compilations in the 
thread section of the hs_err file. Very useful when investigating VMs 
terminated by a timeout.

Testing:
This does not pass all tests yet. A few tests is dependent on the output 
from the diagnostic command, and I want to be sure the reviewers are 
happy with the output format first.

Bug: https://bugs.openjdk.java.net/browse/JDK-8063112
Webrev: http://cr.openjdk.java.net/~neliasso/8063112/webrev.02/

Regards,
Nils