Hi all,

may I please get reviews for this tiny change:

Webrev: http://cr.openjdk.java.net/~stuefe/webrevs/8182864-aix-do-not-assert-in-print-native-callstack/webrev.00/webrev/
Issue: https://bugs.openjdk.java.net/browse/JDK-8182864

In short, this fix removes some asserts from os::print_native_callstack() (via os::Aix::query_stack_dimensions()) which are not really useful. We assert that we do not run on the primordial thread, because otherwise the API used to retrieve the stack dimensions may fail. 

This is wrong on two accounts: 
1) the API now works for the primordial thread too, and does so since AIX 5.3 (?)  and 
2) this is not the right place to assert for the primordial thread, because the stack trace shall always work. 

The assert prevented us to get stack traces in some corner cases where we would have been perfectly able to get them.

For more background on the primordial thread issue on AIX, please see https://bugs.openjdk.java.net/browse/JDK-8171505

Thanks!

Thomas