ghc-8.8.1 release tarball requires alex at ./configure time
GHC release tarballs used not to require
happy and included generated versions of parser and lexer.
ghc-8.8.1 release tarball seems to be different and fails
./configure ... checking for happy... no checking for version of happy... checking for alex... no checking for version of alex... configure: error: Alex version 3.1.7 or later is required to compile GHC.