Use gcc instead of apple-gcc42 when needed.

Library/Contributions/cmd/brew-test-bot.rb

@@ -278,7 +278,7 @@ class Test
       CompilerSelector.new(formula_object).compiler
     rescue CompilerSelectionError => e
       unless installed_gcc
-        test "brew install apple-gcc42"
+        test "brew install gcc"
         installed_gcc = true
         retry
       end

Library/Homebrew/exceptions.rb

@@ -224,7 +224,7 @@ class CompilerSelectionError < Homebrew::InstallationError
     super f, <<-EOS.undent
     #{f.name} cannot be built with any available compilers.
     To install this formula, you may need to:
-      brew install apple-gcc42
+      brew install gcc
     EOS
   end
 end