Fix `YGConfig` constructors
Fix `YGConfig` constructors

Summary:
@public

`YGConfig::YGConfig(YGConfig*)` was not initializing the same fields as the default constructors.

Here, we make the default constructor delegate to the more specialized one to remove duplication.

Reviewed By: SidharthGuglani

Differential Revision: D15164599

fbshipit-source-id: 27247709091b7664386057d09ac67d481877871f

facebook/yoga,facebook/css-layout,facebook/yoga,facebook/yoga,facebook/css-layout,facebook/yoga,facebook/yoga,facebook/css-layout,facebook/css-layout,facebook/css-layout,facebook/css-layout,facebook/yoga,facebook/yoga,facebook/css-layout,facebook/yoga,facebook/yoga,facebook/css-layout,facebook/css-layout,facebook/yoga