Avoid trouble with debugBelch in LLVM version

LLVM obviously requires functions called from Cmm to not be polymorphic.
Previous version used debugBelch to present an error msg to the user
when a parallel primitive was called in a sequential RTS. This version
adjusts arguments to align this use with other uses of debugBelch inside
PrimOps.cmm.
Eliminate some warnings on 64-bit (mostly format strings)