Fix compatibility of MSYS2 dependency installer with bundler

Bundler calls the `Gem.pre_install hook`, but always sets `:ignore_dependencies=>true` in the options.
That's why `bundle install` didn't respect `msys2_mingw_dependencies` in gemspec metadata.
There is no option in bundler to ignore dependencies, so that pacman installation is now forced in the bundler case.

Author: larskanis

resources/files/operating_system.rb

@@ -5,7 +5,7 @@
 Gem.pre_install do |gem_installer|
   RubyInstaller::Runtime.enable_msys_apps(for_gem_install: true) unless gem_installer.spec.extensions.empty?
 
-  unless gem_installer.options && gem_installer.options[:ignore_dependencies]
+  if !gem_installer.options || !gem_installer.options[:ignore_dependencies] || gem_installer.options[:bundler_expected_checksum]
     [['msys2_dependencies'      , :install_packages      ],
      ['msys2_mingw_dependencies', :install_mingw_packages]].each do |metakey, func|