superenv: don't set VERBOSE

haskell-platform falls over badly if VERBOSE is set. Theoretically
this could happen to other packages too. Really it's just less
painful to avoid setting the env var in the first place.

Fixes Homebrew/homebrew#15989.

Library/Homebrew/superenv.rb

@@ -55,7 +55,6 @@ class << ENV
     ENV['CMAKE_INCLUDE_PATH'] = determine_cmake_include_path
     ENV['CMAKE_LIBRARY_PATH'] = determine_cmake_library_path
     ENV['ACLOCAL_PATH'] = determine_aclocal_path
-    ENV['VERBOSE'] = '1' if ARGV.verbose?
   end
 
   def check