bug#36240: indent-code.el is not aware of (package (inherit ...)) style

[Robert Vollmert]

When encountering a package definition that starts

  (package (inherit other-package))

etc/indent-code.el will indent the rest of the package body
to align with the start of (inherit. That seems to be a
common idiom, used in roughly half of the instances:

guix/gnu/packages$ git grep '(inherit ' | wc -l
905
guix/gnu/packages$ git grep '(inherit ' | grep package | wc -l
425