lib/oe/package_manager: bail if createrepo can't be found
If createrepo isn't found then the errors later are mysterious, so explicitly
check and error out early if it isn't there.
(From OE-Core rev:
e09636bbb3ea8ec58984197fd9c691bb908efe00)
(From OE-Core rev:
c87361fc886432a9db584712bf3e41ecd0541960)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
[Fixup do to merge conflicts]
Signed-off-by: Armin Kuster <akuster808@gmail.com>
