__GLASGOW_HASKELL_LLVM__ is no longer an Int

From the user guide (http://ghc.readthedocs.io/en/8.0.1/phases.html#index-8)

__GLASGOW_HASKELL_LLVM__

    Only defined when -fllvm is specified. When GHC is using version x.y.z of LLVM, the value of __GLASGOW_HASKELL_LLVM__ is the integer ⟨xy⟩.

This is not the case, though, due to 29310b62 which changes figureLlvmVersion :: DynFlags -> IO (Maybe Int) into figureLlvmVersion :: DynFlags -> IO (Maybe (Int, Int)), and the driver just showing the result (https://github.com/ghc/ghc/blob/29310b622801733e1b29a9a61988406872db13ca/compiler/main/DriverPipeline.hs#L2084)

As a result, the macro value which used to be a numeric value is now something like (3, 7).

I'm now using a work-around (https://github.com/NicolasT/reedsolomon/commit/9d25ad6a26a29c90b82daacbf406367b8b274c0b), but or the 'tuple value' should become 'official API', or this is a regression to be fixed.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Driver
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