Add capability to get and set the personalitty function from the C API
The capability was lost with D10429 where the personality function was set at function level rather than landing pad level. Now there is no way to get/set the personality function from the C API. That is a problem.
Note that the whole thing could be avoided by improving the C API testing, as started by D10725
Reviewers: chandlerc, bogner, majnemer, andrew.w.kaylor, rafael, rnk, axw
Subscribers: rafael, llvm-commits
Differential Revision: http://reviews.llvm.org/D10946