[XCConfigHelper] Added the ability to inhibit warnings for swift in pod targets.

lib/cocoapods/generator/xcconfig/xcconfig_helper.rb

@@ -284,7 +284,11 @@ module Pod
         def self.add_language_specific_settings(target, xcconfig)
           if target.uses_swift?
             build_settings = {
-              'OTHER_SWIFT_FLAGS' => '$(inherited) ' + quote(%w(-D COCOAPODS)),
+              'OTHER_SWIFT_FLAGS' => [
+                '$(inherited)',
+                quote(%w(-D COCOAPODS)),
+                (quote(["-suppress-warnings"]) if target.try(:inhibit_warnings?) || false),
+              ].compact.join(' '),
             }
             xcconfig.merge!(build_settings)
           end