Use sensible flags for ghc -M

The ghc -M dependency analyser requires you to specify flags in a very obscure way:

  ghc -M -opt-dep-f -opt-depFunnyMakefile -optdep-include-pkg-deps

Simon M writes: "It's historical (because mkdependHS used to be a separate script), but we can't just remove it because there's overlap between the -optdep options and the main GHC options. I don't mind introducing new names for the relevant options."

So the task is to decide names for the flags, implement the change, and document it.

(Currently DriverMkDepend.hs does its own flaggery.)

Trac metadata

Trac field	Value
Version	6.6
Type	Task
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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