Please review: 6541756: Reduce executable C-heap

[Coleen Phillimore]

Summary: Add executable parameters to reserve_memory and commit_memory 
to reduce executable memory to only the Code Heap.

Tested this on solaris, linux (ubuntu) and windows Vista (with nx AlwaysOn)

Webrev:
http://cr.openjdk.java.net/~coleenp/6541756/
Bug:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6541756

Thanks,
Coleen