Fix MIPS exception personality encoding.

For MIPS, we have to encode the personality routine with
an indirect pointer to absptr; otherwise, some link warning
warning will be raised, and the program might crash in some
early MIPS Android device.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209907 91177308-0d34-0410-b5e6-96231b3b80d8