Remove manpage creation. It wasn't working because of help2man
missing when bison is being built. This attempt to create
manpages without help2man turns from no-op to hard error with
automake-1.13.
(From OE-Core rev: a2f4b4437c6d542349d2027330dc16392ed131ae)
Signed-off-by: Marko Lindqvist <cazfi74@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>