Add Data.Utf8 to elm.cabal for 8% allocation reduction

It needs compareByteArrays# which is only available in newer versions
of base and ghc-prim, so this updates those dependencies as well.

The new base and ghc-prim ship with GHC 8.4.3 so I needed to update the
language-glsl constraint as well.

elm.cabal

@@ -163,6 +163,7 @@ Executable elm
         Data.Bag
         Data.Index
         Data.OneOrMore
+        Data.Utf8
         Elm.Compiler.Imports
         Elm.Compiler.Type.Extract
         Elm.Compiler.Version
@@ -232,21 +233,21 @@ Executable elm
     Build-depends:
         ansi-terminal >= 0.8 && < 0.9,
         ansi-wl-pprint >= 0.6.8 && < 0.7,
-        base >=4.8 && <5,
+        base >=4.11 && <5,
         binary >= 0.8 && < 0.9,
         bytestring >= 0.9 && < 0.11,
         containers >= 0.5.8.2 && < 0.6,
         directory >= 1.2.3.0 && < 2.0,
         edit-distance >= 0.2 && < 0.3,
         file-embed,
         filepath >= 1 && < 2.0,
-        ghc-prim,
+        ghc-prim >= 0.5.2,
         haskeline,
         HTTP >= 4000.2.5 && < 4000.4,
         http-client >= 0.5 && < 0.6,
         http-client-tls >= 0.3 && < 0.4,
         http-types >= 0.9 && < 1.0,
-        language-glsl >= 0.0.2 && < 0.3,
+        language-glsl >= 0.3,
         logict,
         mtl >= 2.2.1 && < 3,
         network >= 2.4 && < 2.7,