Fix bugs when running with USE_CODEGEN_DISCOVERY

Summary: Changelog: [internal] Fixing a couple of bugs when running with USE_CODEGEN_DISCOVERY.

Reviewed By: mdvacca

Differential Revision: D33115937

fbshipit-source-id: bb770b406b6dbebfefccac488a7c40caaafa6ca6

Author: sota000

scripts/react_native_pods.rb

@@ -341,7 +341,7 @@ def get_react_codegen_spec(options={})
 end
 
 def get_codegen_config_from_file(config_path, config_key)
-  empty = {'libraries': []}
+  empty = {'libraries' => []}
   if !File.exist?(config_path)
     return empty
   end
@@ -362,7 +362,7 @@ def get_react_codegen_script_phases(options={})
 
   config_file_dir = options[:config_file_dir] ||= ''
   relative_config_file_dir = ''
-  if config_file_dir
+  if config_file_dir != ''
     relative_config_file_dir = Pathname.new(config_file_dir).relative_path_from(Pod::Config.instance.installation_root)
   end