As per gcc PR 11147, libffi installs headers into a target dependent
place (/usr/lib/....). Include a rule to include those files into
libffi-dev package.
Reference: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11147
(From OE-Core rev: 684a4b517d13884c315688967fadd5e6a4845b71)
(From OE-Core rev: 5cb756227b12e0d537430a527c51033572fb627e)
Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>