Temp fixed USB_SERIAL flag issues. Added the boards.build key.
Temp fixed USB_SERIAL flag issues. Added the boards.build key.

adamwolf/chipKIT-core,ricklon/chipKIT-core,majenkotech/chipKIT-core,ricklon/chipKIT-core,majenkotech/chipKIT-core,ricklon/chipKIT-core,adamwolf/chipKIT-core,chipKIT32/chipkit-core,pontech/chipKIT-core,chipKIT32/chipkit-core,adamwolf/chipKIT-core,chipKIT32/chipkit-core,adamwolf/chipKIT-core,majenkotech/chipKIT-core,chipKIT32/chipkit-core,adamwolf/chipKIT-core,EmbeddedMan/chipKIT-core,EmbeddedMan/chipKIT-core,pontech/chipKIT-core,majenkotech/chipKIT-core,pontech/chipKIT-core,EmbeddedMan/chipKIT-core,pontech/chipKIT-core,majenkotech/chipKIT-core,adamwolf/chipKIT-core,pontech/chipKIT-core,pontech/chipKIT-core,ricklon/chipKIT-core,majenkotech/chipKIT-core,EmbeddedMan/chipKIT-core,EmbeddedMan/chipKIT-core,chipKIT32/chipkit-core,EmbeddedMan/chipKIT-core,ricklon/chipKIT-core,majenkotech/chipKIT-core,adamwolf/chipKIT-core,EmbeddedMan/chipKIT-core,ricklon/chipKIT-core,pontech/chipKIT-core