[PATCH] Update API to add PIC-level support.

[Justin Hibbits]

>>! In D5332#9, @mcrosier wrote:
> Just a few nits.
> 
> (If this isn't already being done in another patch) Can you add some amount of functionality, so this can be tested in some trivial way?
> 
> Unfortunately, I'm not the right person to sign off on this..

Thanks for reviewing.  This is just the plumbing patch.  The real meat (the reason I created this in the first place) is in D5399, adding -fpic (small-model PIC) to PowerPC.  This is accompanied by tests.

This patch itself should have no impact on functionality, only on API usage, which D5400 demonstrates for Clang.  So, really, D5400 and this belong together, since Clang breaks without the patch in D5400.

http://reviews.llvm.org/D5332