Bash headers path changed in 4.4 (core-updates)

[Leo Famulari]

While looking at the build failure of recutils on core-updates [0], I
noticed that the directory structure of bash:include changed from 4.3 to
4.4.

Using stdc.h as an example, For 4.3, our package creates a tree like this:
./include/bash/stdc.h

For 4.4, it's like this:
./include/bash/include/stdc.h

Is this intentional?

[0]
https://hydra.gnu.org/build/1538148/log/tail-reload