ext module fiddle depend on libffi, in ruby source tree,
there is in internal libffi in case target platfrom don't
install libffi, but autotools.bbclass delete configure
under libffi and not run autoreconf to regenerate one.so
we met this error:
ruby-2.5.3/ext/fiddle/libffi-3.2.1/configure: No such file or directory
the fix is add depend and extra_oeconf to use libffi in the system
Signed-off-by: Changqing Li <changqing.li@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>