Heads up: top level `make test` now runs the full testsuite

Typing `make test` in the ghc root directory now runs the full testsuite, just like it already did in the `testsuite/tests` directory. If you want to run the fast testsuite, use the new targets `make fasttest` or `make fast`. The `validate` script still runs the same tests as before (depending on the argument, `--slow`, `--fast` or normal). References: https://ghc.haskell.org/trac/ghc/wiki/Building/StandardTargets#Topleveltarge... https://ghc.haskell.org/trac/ghc/wiki/Building/RunningTests -Thomas Miedema