[PATCH] light up ASan on ARM. XFAILed failing tests

[Greg Fitzgerald]

Some are just ARM Linux (fast unwind not working as expected and giving us bad stack traces).  Some are triggering segfaults when looking up shadow memory.  Some hang and might indicate qemu-arm bugs - those are marked "REQUIRES: stable-runtime" in this patch.

I can't commit to fixing all the XFAILs before the 3.5 release.  Would anyone be able to lend a hand?  I think the first step would be to set up a qemu-arm bot so that we can standardize on a runtime environment and configuration.  For instance, to get ASan to start up, I had to configure qemu to reserve zero bytes for guest virtual address space (-R 0) and I don't understand why that is needed.  

As for Android, I hear the Android emulator is based on qemu.  Maybe this bot can build and test both arm-linux and android?

http://reviews.llvm.org/D3857