Return R_PLT_PC for R_PPC_PLTREL24.
Return R_PLT_PC for R_PPC_PLTREL24.

The PPC port doesn't support PLT yet, but the architecture independent
code optimizes PLT access for non preemptible symbols, which is
exactly what returning R_PC was trying to implement.

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@320430 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld