RFR(XS): 8174768: Make ProcessTools print executed process output into a separate file

[Evgeny Nikitin]

Hi, 


Bug: https://bugs.openjdk.java.net/browse/JDK-8174768 

Webrev: http://cr.openjdk.java.net/~iignatyev/enikitin/8174768/webrev.00/ 


The bug had been created as a request to simplify investigation for compiler control tests failures. 
I found the functionality pretty generic and useful and made ProcessTools dump output as well as some diagnostic information for every executed process into a separate file. 
The diagnostic information contains cmdline, exit code, stdout and stderr. The output files are named like 'pid-<PID>-output.log'. 

The change has been tested via a mach5 test runs (jdk-tier1 through 4) on the 4 common platforms (linux-x64, windows-x64, macosx-x64, sparcv9). 

Please review, 
/Evgeny Nikitin.