runqueue/build: Add recideptask flag

Currently, tasks like fetchall are slightly broken since if a recipe
has specific [depends] which occur after do_fetch and add items not listed
in DEPENDS and RDEPENDS, they are not caught by recrdeptask. We've gone
around in circles on this issue (e.g
http://git.yoctoproject.org/cgit.cgi/poky/commit/bitbake/lib/bb/runqueue.py?id=5fa6036d49ed7befe6ad50ec95c61a50aec48195
) and in many cases the behaviour of recrdepends is correct but tasks like
fetchall need the other behaviour.

To address this we add a recideptask flag which can be used in conjuction
with the recrdeptask flag to specify which task to to the inspection upon.
This means entries like do_rootfs[depends] which have do_fetch tasks are
caught and run.

I'm not 100% happy with needing another flag but I don't see any rational
way to get the correct behaviour in all cases without it.

[YOCTO #4597]

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
fetch2: Enhance error message for BB_NO_NETWORK

BB_NO_NETWORK can be set by bitbake internally by the use of
BB_FETCH_PREMIRRORONLY so update the error message to give users a
hint about this.

[YOCTO #3222]

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>