Initial patchset to get the testsuite running against armv7 and arm64 iOS devices.

Normal customer devices won't be able to run these tests, we're hoping to get
a public facing bot set up at some point.  Both devices pass the testsuite without
any errors or failures.

I have seen some instability with the armv7 test runs, I may submit additional patches
to address this.  arm64 looks good.

I'll be watching the bots for the rest of today; if any problems are introduced by
this patch I'll revert it - if anyone sees a problem with their bot that I don't
see, please do the same.  I know it's a rather large patch.

One change I had to make specifically for iOS devices was that debugserver can't 
create files.  There were several tests that launch the inferior process redirecting
its output to a file, then they retrieve the file.  They were not trying to test
file redirection in these tests, so I rewrote those to write their output to a file
directly.

llvm-svn: 314132