Clearer call to action (thanks @trevorturk)

require_gcc() {

  local gcc="$(locate_gcc || true)"

  if [ -z "$gcc" ]; then

    local esc=$'\033'

    { echo

      echo "ERROR: This package must be compiled with GCC, but ruby-build couldn't"

      echo "${esc}[1mERROR${esc}[0m: This package must be compiled with GCC, but ruby-build couldn't"

      echo "find a suitable \`gcc\` executable on your system. Please install GCC"

      echo "and try again."

      echo

      if [ "$(uname -s)" = "Darwin" ]; then

        local esc=$'\033'

        echo "Apple no longer includes the official GCC compiler with Xcode as of"

        echo "version 4.2. Instead, the \`gcc\` executable is a symlink to \`llvm-gcc\`,"

        echo "a modified version of GCC which outputs LLVM bytecode."

        echo "${esc}[1mDETAILS${esc}[0m: Apple no longer includes the official GCC compiler with Xcode"

        echo "as of version 4.2. Instead, the \`gcc\` executable is a symlink to"

        echo "\`llvm-gcc\`, a modified version of GCC which outputs LLVM bytecode."

        echo

        echo "For most programs the \`llvm-gcc\` compiler works fine. However,"

        echo "versions of Ruby older than 1.9.3-p125 are incompatible with"

        echo "\`llvm-gcc\`. To build older versions of Ruby you must have the official"

        echo "GCC compiler installed on your system."

        echo

        echo "You can install the official GCC compiler on OS X using these binary"

        echo "${esc}[1mTO FIX THE PROBLEM${esc}[0m: Install the official GCC compiler using these"

        echo "packages: ${esc}[4mhttps://github.com/kennethreitz/osx-gcc-installer/downloads${esc}[0m"

        echo

        echo "You will need to install the official GCC compiler to build older"