Enable ios on Raspberry Pi

Adds more jobs to iOS testing and switches to 
RPi based hosts. 

Bug: skia:
Change-Id: I0124c6554173fa3b22b077a198612bb30691d1fb
Reviewed-on: https://skia-review.googlesource.com/11521
Commit-Queue: Stephan Altmueller <stephana@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
11 files changed