[CocoaPods] Use modular headers

http://blog.cocoapods.org/CocoaPods-1.5.0/#modular-headers

Author: ikesyo

Nimble.podspec

@@ -42,6 +42,7 @@ Pod::Spec.new do |s|
   s.compiler_flags = '-DPRODUCT_NAME=Nimble/Nimble'
   s.pod_target_xcconfig = {
     'APPLICATION_EXTENSION_API_ONLY' => 'YES',
+    'DEFINES_MODULE' => 'YES',
     'ENABLE_BITCODE' => 'NO',
     'OTHER_LDFLAGS' => '$(inherited) -weak-lswiftXCTest -Xlinker -no_application_extension',
     'OTHER_SWIFT_FLAGS' => '$(inherited) -suppress-warnings',

script/release

@@ -173,7 +173,7 @@ echo
 echo "Pushing to pod trunk..."
 
 # NOTE: remove allow-warnings after v9.0.0 of Nimble
-$POD trunk push "$PODSPEC" --allow-warnings
+$POD trunk push "$PODSPEC" --allow-warnings --skip-import-validation
 
 echo
 echo "================ Finalizing the Release ================"