Fix compilation error using arch i386

Adding a member variable to hold the `placeholderAttributes` property fixes a compilation error regarding synthesis when building with ARCH=i386.
closed #5188, fixed android NULL pointer exception
Merge pull request #18 from andyque/xxx

issue #323, hehe
Merge pull request #6764 from minggo/monkey-test

EditBox: Check text content before being sent to cpp
Update config.gitingore
[AUTO][ci skip]: updating cocos2dx_files.json
Merge pull request #6765 from CocosRobot/update_cocosfiles_1400149858

[AUTO][ci skip]: updating cocos2dx_files.json
Merge pull request #6744 from NatWeiss/patch-8

Fix compilation error using arch i386
[ci skip]