PPC: Handle right shift of > 31 bits. Fix #5999.
PPC: Handle right shift of > 31 bits. Fix #5999.

MERGED from commit 42c8e80165bb087493b95a768bbbf276870c7056

ilyasergey/GHC-XAppFix,ilyasergey/GHC-XAppFix,ilyasergey/GHC-XAppFix,ilyasergey/GHC-XAppFix