RFR: 7181175 Enable hotspot builds on Windows with MinGW/MSYS

[Tim Bell]

All-

This is the hotspot-only portion of the changes to allow building on 
Windows with any of MKS, Cygwin, or MinGW/MSYS as the 'Unix-like' shell 
environment:

http://cr.openjdk.java.net/~tbell/7181175/webrev.00/

A Windows-only JPRT build/test run was successful: job 
2012-07-02-230003.tbell.hotspot

Bug fix #7152336 [1] will be used to update the other repos after these 
changes are in hotspot.

I'd like a quick review from some HS runtime members, and then I will 
need to ask for a volunteer to push the change in (unless I can do that 
myself by submitting to JPRT... glad to do it if it is OK).

Thanks in advance-

Tim Bell


[1] http://cr.openjdk.java.net/~tbell/7152336/webrev.02/