RFR(S): 6885993: Named Thread: introduce print() and print_on(outputStream* st) methods

[Zhengyu Gu]

This is more of code cleanup. Instead of duplicating similar code all 
over subclasses of NamedThread, NamedThread should implements 
print_on(outputStream* str) and its subclasses should only set "name" to 
use default the implementation.

Webrev: http://cr.openjdk.java.net/~zgu/6885993/webrev.00/
Bug: https://bugs.openjdk.java.net/browse/JDK-6885993

Tests:
   - JPRT
   - Ran a Java program on Linux x64, do "CTRL-\" to dump Java stacks, 
make sure the output remains unchange.

Thanks,

-Zhengyu