Revert "Use template haskell to fix the call to withTempDirectory in Setup.hs so that it works with Cabal 1.17".

It turns out this will not be changing in 1.18 (official Cabal release), so we need to revert this change. https://github.com/haskell/cabal/issues/1387

This reverts commit aa709c52fd3d9ff77738d739304e40d195eea3e1.
Merge pull request #7 from hamishmack/master

Revert "Use template haskell to fix the call to withTempDirectory in Setup.hs so that it works with Cabal 1.17"