RFR 8042727: nsk/jdb/unwatch/unwatch001 crash in InstanceKlass::methods_do(void (*)(Method*))

[Coleen Phillimore]

Summary: Only walk methods in instanceklass if the class is loaded

The bug was caused by walking methods in the CLDG while some classes 
were still being loaded, so you could get null for methods().  I also 
changed print_method_statistics to not unconditionally walk the CLDG 
methods at exit if there are no CompilerOracle print options.

Tested with regression/other/RuntimeTest which crashed within an hour 
with this bug, and never with the fix.
Also ran jtreg tests, and manually tested .hotspot_compiler prints a 
method requested.  I didn't add a test because there should be some 
other compiler print tests already and this would be a small meaningless 
test.

open webrev at http://cr.openjdk.java.net/~coleenp/8042727/
bug link https://bugs.openjdk.java.net/browse/JDK-8042727

Thanks,
Coleen