Add hostArchitectures to macOS Distribution file

Unless hostArchitectures is set, macOS 11 will assume that the package
is x86_64 and require Rosetta 2.

* https://scriptingosx.com/2020/12/platform-support-in-macos-installer-packages-pkg/
* https://developer.apple.com/library/archive/documentation/DeveloperTools/Reference/DistributionDefinitionRef/Chapters/Distribution_XML_Ref.html#//apple_ref/doc/uid/TP40005370-CH100-SW7

Cherry-picked-from: chef/omnibus@6173b5f

Author: tduffield

lib/omnibus/packagers/pkg.rb

@@ -242,6 +242,7 @@ def write_distribution_file
                         identifier: safe_identifier,
                         version: safe_version,
                         component_pkg: component_pkg,
+                        host_architecture: safe_architecture,
                       })
     end
 

resources/pkg/distribution.xml.erb

@@ -7,7 +7,7 @@
 
   <!-- Generated by productbuild - - synthesize -->
   <pkg-ref id="<%= identifier %>"/>
-  <options customize="never" require-scripts="false"/>
+  <options customize="never" require-scripts="false" hostArchitectures="<%= host_architecture %>" />
   <choices-outline>
     <line choice="default">
       <line choice="<%= identifier %>"/>

spec/unit/packagers/pkg_spec.rb

@@ -137,8 +137,24 @@ module Omnibus
 
         expect(contents).to include('<pkg-ref id="com.getchef.project-full-name"/>')
         expect(contents).to include('<line choice="com.getchef.project-full-name"/>')
+        expect(contents).to include('hostArchitectures="x86_64"')
         expect(contents).to include("project-full-name-core.pkg")
       end
+
+      context "for arm64 builds" do
+        before do
+          stub_ohai(platform: "mac_os_x", version: "11.0") do |data|
+            data["kernel"]["machine"] = "arm64"
+          end
+        end
+
+        it "sets the hostArchitectures to include arm64" do
+          subject.write_distribution_file
+          contents = File.read("#{staging_dir}/Distribution")
+
+          expect(contents).to include('hostArchitectures="arm64"')
+        end
+      end
     end
 
     describe '#build_product_pkg' do