RFR (S): 8184073: Cleanup of compiler activity enum in compileBroker.hpp

[Erik Österlund]

Hi,

Bug:
https://bugs.openjdk.java.net/browse/JDK-8184073

Webrev:
http://cr.openjdk.java.net/~eosterlund/8184073/webrev.00/

This is a small cleanup to fix two problems with an unnamed enum in 
compileBroker.hpp:

   enum {
     // Flags for toggling compiler activity
     stop_compilation    = 0,
     run_compilation     = 1,
     shutdown_compilaton = 2
   };

1) This is an unnamed enum. That means it can not be passed to template 
functions. It is passed to Atomic::xchg, and there are plans to make 
Atomic use templates, which is blocked by this unnamed enum, and this 
enum alone. Therefore I have given it a name describing the values: 
"CompilerActivity".
2) The "shutdown_compilaton" value is misspelled and since I am touching 
this code, I feel it is my responsibility to correct that. And so I did.

Testing: JPRT.

Thanks,
/Erik