Add compiler flags on each Spec in target

spec_arc_support.rb

require 'xcodeproj'

project = Xcodeproj::Project.new 'SomeProject.xcodeproj'
target = project.targets.last
build_phase = target.source_build_phase
files = build_phase.files
settings = { 'COMPILER_FLAGS' => '-fno-objc-arc' }
files.each do |f|
  if f.display_name =~ /Spec/
    if f.settings
      f.settings = f.settings.merge settings
    else
      f.settings = settings
    end
    puts f.display_name
  end
end