Fix more bad dump_verbose_config references

Follow-up to c7edf9a063dce63afb9ab54b6d71fe864d578365 and related to
changes from #168.

Library/Homebrew/exceptions.rb

@@ -330,14 +330,14 @@ class BuildError < RuntimeError
         end
       end
     else
-      require "cmd/config"
+      require "system_config"
       require "build_environment"
 
       ohai "Formula"
       puts "Tap: #{formula.tap}" if formula.tap?
       puts "Path: #{formula.path}"
       ohai "Configuration"
-      Homebrew.dump_verbose_config
+      SystemConfig.dump_verbose_config
       ohai "ENV"
       Homebrew.dump_build_env(env)
       puts

Library/Homebrew/formula.rb

@@ -1482,12 +1482,12 @@ class Formula
         end
         log.puts
 
-        require "cmd/config"
+        require "system_config"
         require "build_environment"
 
         env = ENV.to_hash
 
-        Homebrew.dump_verbose_config(log)
+        SystemConfig.dump_verbose_config(log)
         log.puts
         Homebrew.dump_build_env(env, log)