Require only one pass to make BR.java file.

Bug 19985005

Because the generation of Binding files created @Bindable
annotations, the BR file generation had to wait until a
second annotation pass. This caused errors to be generated
that were later cleared, causing confusion. I moved the
BR file generation to the same annotation processing stage
that generates the Binding files to clear up the error
generation.

TODO: merge the annotation processing stages so that there
is less cross-talk between annotation processors.