[XCConfigIntegrator] Make the check for xcconfig_includes_target_xcconfig? more concise

lib/cocoapods/installer/user_project_integrator/target_integrator/xcconfig_integrator.rb

@@ -150,7 +150,7 @@ module Pod
           #
           SILENCE_WARNINGS_STRING = '// @COCOAPODS_SILENCE_WARNINGS@ //'
           def self.xcconfig_includes_target_xcconfig?(base_config_ref, target_config_path)
-            return unless base_config_ref && File.exist?(base_config_ref.real_path)
+            return unless base_config_ref && base_config_ref.real_path.file?
             regex = /
               ^(
                 (\s*                                  # Possible, but unlikely, space before include statement
@@ -164,8 +164,7 @@ module Pod
                 (#{Regexp.quote(SILENCE_WARNINGS_STRING)}) # Token to treat xcconfig as good and silence pod install warnings
               )
             /x
-            File.foreach(base_config_ref.real_path) { |line| return true if line =~ regex }
-            false
+            base_config_ref.real_path.readlines.find { |line| line =~ regex }
           end
         end
       end