Properly dereference 64-bit PPC ELF V1 ABIT function pointers to signal handlers.
On this platform, function pointers are pointers to structures and the first 64
bits of such a structure contains the function's entry point.  The second 64 bits
contains the TOC pointer, which must be placed into GPR 2.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>