[bundler/bundler] Remove now meaningless setting

https://github.com/bundler/bundler/commit/52c5a0eede

lib/bundler/inline.rb

@@ -60,7 +60,7 @@ def gemfile(install = false, options = {}, &gemfile)
 
     Bundler.ui = ui if install
     if install || missing_specs.call
-      Bundler.settings.temporary(:inline => true, :disable_platform_warnings => true) do
+      Bundler.settings.temporary(:inline => true) do
         installer = Bundler::Installer.install(Bundler.root, definition, :system => true)
         installer.post_install_messages.each do |name, message|
           Bundler.ui.info "Post-install message from #{name}:\n#{message}"

lib/bundler/settings.rb

@@ -25,7 +25,6 @@ module Bundler
       disable_exec_load
       disable_local_branch_check
       disable_multisource
-      disable_platform_warnings
       disable_shared_gems
       disable_version_check
       force_ruby_platform

man/bundle-config.ronn

@@ -176,8 +176,6 @@ learn more about their operation in [bundle install(1)](bundle-install.1.html).
    When set, Gemfiles containing multiple sources will produce errors
    instead of warnings.
    Use `bundle config unset disable_multisource` to unset.
-* `disable_platform_warnings` (`BUNDLE_DISABLE_PLATFORM_WARNINGS`):
-   Disable warnings during bundle install when a dependency is unused on the current platform.
 * `disable_shared_gems` (`BUNDLE_DISABLE_SHARED_GEMS`):
    Stop Bundler from accessing gems installed to RubyGems' normal location.
 * `disable_version_check` (`BUNDLE_DISABLE_VERSION_CHECK`):