title: Build failed with NonZeroExit 77 when installing Haskell on Mac, ghcup --cache install" failed
body: <p>Does anyone know how to fix this error?
  I am currently trying to install Haskell on Mac using the instructions from <a href="https://www.haskell.org/ghcup/" rel="nofollow noreferrer">https://www.haskell.org/ghcup/</a>.</p>
  
  <p>Installation starts with the following command line:</p>
  
  <pre><code>curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | sh
  </code></pre>
  
  <p>However at a certain moment I receive this error:</p>
  
  <pre><code>Build failed with NonZeroExit 77 "./configure" ["--prefix=/Users/not_root/.ghcup/ghc/8.8.3"]
  Check the logs at ~/.ghcup/logs and the build directory"/var/folders/n0/g0qh09_s46ndjzmy1jctj7f00000gr/T/ghcup-iyHoc8/ghc-8.8.3" for more clues.
  
  "ghcup --cache install" failed!
  </code></pre>
  
  <p>This are the log files:
  ghc-configure.log:</p>
  
  <pre><code>checking for gcc... gcc
  checking whether ln -s works... yes
  checking for gsed... sed
  checking XCode version... xcode-select: error: tool 'xcodebuild'requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance
  not found (too old?)
  checking for gcc... gcc
  checking whether the C compiler works... no
  checking for gsed... sed
  checking XCode version... xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance
  not found (too old?)
  checking for gcc... gcc
  checking whether the C compiler works... no
  configure: error: in `/private/var/folders/n0/g0qh09_s46ndjzmy1jctj7f00000gr/T/ghcup-iyHoc8/ghc-8.8.3':
  checking XCode version... xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance
  not found (too old?)
  checking for gcc... gcc
  checking whether the C compiler works... no
  configure: error: in `/private/var/folders/n0/g0qh09_s46ndjzmy1jctj7f00000gr/T/ghcup-iyHoc8/ghc-8.8.3':
  configure: error: C compiler cannot create executables
  not found (too old?)
  checking for gcc... gcc
  checking whether the C compiler works... no
  configure: error: in `/private/var/folders/n0/g0qh09_s46ndjzmy1jctj7f00000gr/T/ghcup-iyHoc8/ghc-8.8.3':
  configure: error: C compiler cannot create executables
  See `config.log' for more details
  </code></pre>
  
  <p>This is the ghcup.log:</p>
  
  <pre><code>Debug:  Receiving download info from: GHCupURL
  Debug:  Unable to get/parse Last-Modified header
  Debug:  Requested to install GHC with Version {_vEpoch = Nothing, _vChunks = [[Digits 8],[Digits 8],[Digits 3]], _vRel = []}
  Debug:  Identified Platform as: PlatformResult {_platform = Darwin, _distroVersion = Just (General (Version {_vEpoch = Nothing, _vChunks = [[Digits 10],[Digits 15]], _vRel = []}))}
  Info: downloading: https://downloads.haskell.org/~ghc/8.8.3/ghc-8.8.3-x86_64-apple-darwin.tar.xz
  Info: verifying digest of: /Users/not_root/.ghcup/cache/ghc-8.8.3-x86_64- apple-darwin.tar.xz
  Info: Unpacking: /Users/not_root/.ghcup/cache/ghc-8.8.3-x86_64-apple-darwin.tar.xz
  Info: Installing GHC (this may take a while)
  Error: Build failed with NonZeroExit 77 "./configure" ["--prefix=/Users/not_root/.ghcup/ghc/8.8.3"]
  Check the logs at ~/.ghcup/logs and the build directory "/var/folders/n0/g0qh09_s46ndjzmy1jctj7f00000gr/T/ghcup-iyHoc8/ghc-8.8.3" for more clues.
  </code></pre>