[Installer] Create FileAccessors only once per each PodTarget

By iterating over the uniq pod targets, instead of all pod targets per aggregate target, where now the same PodTarget can occur multiple times.

lib/cocoapods/installer.rb

@@ -262,16 +262,14 @@ module Pod
     #       created by the Pod source installer as well.
     #
     def create_file_accessors
-      aggregate_targets.each do |target|
-        target.pod_targets.each do |pod_target|
-          pod_root = sandbox.pod_dir(pod_target.root_spec.name)
-          path_list = Sandbox::PathList.new(pod_root)
-          file_accessors = pod_target.specs.map do |spec|
-            Sandbox::FileAccessor.new(path_list, spec.consumer(pod_target.platform))
-          end
-          pod_target.file_accessors ||= []
-          pod_target.file_accessors.concat(file_accessors)
+      pod_targets.each do |pod_target|
+        pod_root = sandbox.pod_dir(pod_target.root_spec.name)
+        path_list = Sandbox::PathList.new(pod_root)
+        file_accessors = pod_target.specs.map do |spec|
+          Sandbox::FileAccessor.new(path_list, spec.consumer(pod_target.platform))
         end
+        pod_target.file_accessors ||= []
+        pod_target.file_accessors.concat(file_accessors)
       end
     end