opkg: Add support for excluding packages from the install

opkg: Add support for excluding packages from the install

This adds a new argument to opkg-cl, --add-exclude, which is
used to add package names to the list of packages to exclude
from the install.

If an excluded package is needed for the install to resolve,
an error will be generated.  Recommended packages will not
generate an error.

(From OE-Core rev: 63c61b7c0c8aeb89661e3bb85e281dd1ef5b618c)

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>