PPC NCG: Rename constructors
PPC NCG: Rename constructors

Rename constructors in calling convention data type to reflect the
fact that they represent an ELF ABI not only a Linux ABI.

sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc