Fix Base constraint, remove support for »old base«

Since support for GHC <= 7.2 was recently dropped, the Base constraint
was incorrect (…it was before as well, claiming any base >= 3 would
work).

Resolves #13
Thanks @hvr

ansi-wl-pprint.cabal

@@ -1,5 +1,5 @@
 name:                ansi-wl-pprint
-version:             0.6.8
+version:             0.6.8.1
 cabal-version:       >= 1.6
 category:            User Interfaces, Text
 synopsis:            The Wadler/Leijen Pretty Printer for colored ANSI terminal output
@@ -19,7 +19,7 @@ source-repository head
   location: git://github.com/ekmett/ansi-wl-pprint.git
 
 flag NewBase
-  description:    Choose the new smaller, split-up base package with 6.10
+  description:    UNUSED! This flag was once there for compatibility reasons.
   default:        True
 
 flag Example
@@ -39,19 +39,13 @@ library
     build-depends: semigroups >= 0.1 && < 0.19
 
   build-depends: ansi-terminal >= 0.4.0 && < 0.7
-  if flag(newbase)
-    build-depends:  base >= 3 && < 5
-  else
-    build-depends:  base < 3
+  build-depends:  base >= 4.5 && < 5
 
 executable ansi-wl-pprint-example
   main-is: Text/PrettyPrint/ANSI/Example.hs
 
   build-depends: ansi-terminal >= 0.4.0 && < 0.7
-  if flag(newbase)
-    build-depends:  base >= 3 && < 5
-  else
-    build-depends:  base < 3
+  build-depends:  base >= 4.5 && < 5
 
   if !flag(example)
     buildable:      False