[PATCH] Enable EHABI by default on non-Darwin ARM targets

[Renato Golin]

  Hi Anton,

  I kept the option as "-arm-disable-ehabi", but requiring all MCJIT users to start using them would be cheeky. Meanwhile, I'll have a look at which relocation is missing and try to implement it, but that might not be the only problem and I could spend a huge time chasing the wrong problem.

  The main issue with the MCAsmInfo is that there is no way to turn it on/off dynamically (only based on that flag and being ELF), so another possibility would be to add a dynamic disableEH() and call it from MCJIT's drivers. I'll do this one first and add to this commit and chase the relocation later. We should be able to remove this method once everything works fine for a while.

http://llvm-reviews.chandlerc.com/D2627