gnu: Add ghc-tasty.

* gnu/packages/haskell.scm (ghc-tasty): New variable.

gnu: Add ghc-clock-bootstrap.

The ghc-clock-bootstrap package has tests disabled, since they
themselves indirectly require ghc-clock.  After adding ghc-tasty and
ghc-tasty-quickcheck, ghc-clock is defined as a public package with
tests enabled.

* gnu/packages/haskell.scm (ghc-clock-bootstrap): New variable.

gnu: Add ghc-stringsearch.

* gnu/packages/haskell.scm (ghc-stringsearch): New variable.

gnu: Add ghc-word8.

* gnu/packages/haskell.scm (ghc-word8): New variable.

gnu: Add ghc-lifted-base.

* gnu/packages/haskell.scm (ghc-lifted-base): New variable.

gnu: Add ghc-regex-tdfa-rc.

* gnu/packages/haskell.scm (ghc-regex-tdfa-rc): New variable.

gnu: Add ghc-charset.

* gnu/packages/haskell.scm (ghc-charset): New variable.

gnu: Add ghc-fast-logger.

* gnu/packages/haskell.scm (ghc-fast-logger): New variable.

gnu: Add ghc-bytestring-builder.

* gnu/packages/haskell.scm (ghc-bytestring-builder): New variable.

gnu: Add ghc-tagsoup.

* gnu/packages/haskell.scm (ghc-tagsoup): New variable.

gnu: Add ghc-digest.

* gnu/packages/haskell.scm (ghc-digest): New variable.

gnu: Add ghc-contravariant.

* gnu/packages/haskell.scm (ghc-contravariant): New variable.

gnu: Add ghc-statevar.

* gnu/packages/haskell.scm (ghc-statevar): New variable.

gnu: Add ghc-bifunctors.

* gnu/packages/haskell.scm (ghc-bifunctors): Add variable.

gnu: Add ghc-void.

* gnu/packages/haskell.scm (ghc-void): New variable.

gnu: Add ghc-semigroups.

* gnu/packages/haskell.scm (ghc-semigroups): New variable.

gnu: Add ghc-nats.

* gnu/packages/haskell.scm (ghc-nats): New variable.

gnu: Add ghc-http-types.

* gnu/packages/haskell.scm (ghc-http-types): New variable.

gnu: Add ghc-quickcheck-instances.

* gnu/packages/haskell.scm (ghc-quickcheck-instances): New variable.

gnu: Add ghc-unix-compat.

* gnu/packages/haskell.scm (ghc-unix-compat): New variable.