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.
modify /merge to /head in pull-request-build.
closed #5188, fixed android NULL pointer exception
Merge pull request #18 from andyque/xxx

issue #323, hehe
[ci skip], modify build-job termination time.
modify build terminal time in watchdog.py.[ci skip]
Merge pull request #6760 from shujunqiao/watchdog

[ci skip], modify build-job termination time.
Merge pull request #6761 from samuele3hu/v3_fix

Update some GuiConstants and resubmission pr#6361.
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]
multiple pass sprite

on ShaderSprite2.cpp
Merge pull request #6767 from ricardoquesada/sprite_multiple_pass

multiple pass sprite
uniform sampler CC_Texture0 MUST NOT be defined on shaders

since it is a built-in.
Built-in uniforms MUST NOT be defined on shaders.
Basically all CC_ uniforms must be defined by cocos2d-x
Merge pull request #6768 from ricardoquesada/uniform_texture_0

uniform sampler CC_Texture0 MUST NOT be defined on shaders
default value is 0.5 for interpolation
Merge pull request #6769 from ricardoquesada/interpolate_fix

default value is 0.5 for interpolation