Cabalify all the things

Adding cabal files to `unlit`, `touchy` and `hp2ps`, allows us to treat
them uniformally across the build system. In particular Hadrian will use
these.

Reviewers: bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D4192

utils/hp2ps/hp2ps.cabal

+cabal-version: >=2.1
+Name: hp2ps
+Version: 0.1
+Copyright: XXX
+License: BSD3
+Author: XXX
+Maintainer: XXX
+Synopsis: Heap Profile to PostScript converter
+Description: XXX
+Category: Development
+build-type: Simple
+
+Executable unlit
+    Default-Language: Haskell2010
+    Main-Is: Main.c
+    extra-libraries: m
+    C-Sources:
+       AreaBelow.c Curves.c Error.c Main.c
+       Reorder.c TopTwenty.c AuxFile.c Deviation.c
+       HpFile.c Marks.c Scale.c TraceElement.c
+       Axes.c Dimensions.c Key.c PsFile.c Shade.c
+       Utilities.c

utils/touchy/touchy.cabal

+cabal-version: >=2.1
+Name: touchy
+Version: 0.1
+Copyright: XXX
+License: BSD3
+Author: XXX
+Maintainer: XXX
+Synopsis: @touch@ for windows
+Description: XXX
+Category: Development
+build-type: Simple
+
+Executable unlit
+    Default-Language: Haskell2010
+    Main-Is: touchy.c
+    C-Sources: touchy.c

utils/unlit/unlit.cabal

+cabal-version: >=2.1
+Name: unlit
+Version: 0.1
+Copyright: XXX
+License: BSD3
+Author: XXX
+Maintainer: XXX
+Synopsis: Literate program filter
+Description: XXX
+Category: Development
+build-type: Simple
+
+Executable unlit
+    Default-Language: Haskell2010
+    Main-Is: unlit.c
+    C-Sources: unlit.c