Adds hoisting from zippered iterators 

(whoops, I thought I committed this yesterday, but I guess my svn hung)

[reviewed by sung] 

Previously, zippered iterators did not have LICM performed on them. In the
function that collected the loops from a function, empty basic blocks were
ignored. Since zippered iterator loops had empty basic blocks at the end of
them, they were never identified as loops, and thus never hoisted from. To
correct this empty basic blocks cannot be ignored. The problem with this was
that empty basic blocks were sometimes dead empty basic blocks. The dominator
analysis assumed that no blocks were dead, which lead to things that were not
loops being identified as loops, and subsequently being hoisted from. This
patch corrects the dominator analysis so that empty basic blocks are not
ignored and thus zippered iterators will be hoisted from. 

There should be some nice performance benefits from this patch, as a bunch more
loops will now be hoisted from. Additionally, this should also fix the
regression in test/users/ferguson/aa/aa1.chpl.  


git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@21886 3a8e244f-b0f2-452b-bcba-4c88e055c3ca
Set up a default for Cray Cluster Solutions (CCS) machines. [reviewed by Brad]

CCS machines utilize an Infiniband connection, so their default comm_substrate
should be ibv.  I added this default value to util/chplenv/commSubstrate and
added documentation for CCS to doc/release/README.chplenv and
doc/release/README.multilocale, and a description of how to set up for CCS to
doc/release/platforms/README.cray-cs.

In addition, I fixed some tabbing that was bugging me in util/chplenv/launcher
and the README files I edited.


git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@21887 3a8e244f-b0f2-452b-bcba-4c88e055c3ca
Changed Cray Cluster Solutions references to Cray CS references based on Greg's
recommendations.

Also altered the steps in doc/release/platforms/README.cray-cs to reflect Brad's
comments.



git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@21888 3a8e244f-b0f2-452b-bcba-4c88e055c3ca
updated README, fixed data file bug, correcting testing system files

git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@21889 3a8e244f-b0f2-452b-bcba-4c88e055c3ca