Add ruby target to --config

bin/brew

@@ -48,6 +48,8 @@ def dump_config
  sha = `cd #{HOMEBREW_REPOSITORY} && git rev-parse --verify HEAD 2> /dev/null`.chomp
  kernel_arch = `uname -m`.chomp
 
+ system_ruby = Pathname.new("/usr/bin/ruby")
+
  puts <<-EOS
 HOMEBREW_VERSION: #{HOMEBREW_VERSION}
 HEAD: #{sha}
@@ -59,6 +61,7 @@ Hardware: #{cores}-core #{bits}-bit #{Hardware.intel_family}
 OS X: #{MACOS_FULL_VERSION}
 Kernel Architecture: #{kernel_arch}
 Ruby: #{RUBY_VERSION}-#{RUBY_PATCHLEVEL}
+/usr/bin/ruby => #{system_ruby.realpath}
 GCC-4.0: #{gcc_40 ? "build #{gcc_40}" : "N/A"} (#{RECOMMENDED_GCC_40} or newer recommended)
 GCC-4.2: #{gcc_42 ? "build #{gcc_42}" : "N/A"} (#{RECOMMENDED_GCC_42} or newer recommended)
 LLVM: #{llvm ? "build #{llvm}" : "N/A" } #{llvm ? "(#{RECOMMENDED_LLVM} or newer recommended)" : "" }