salt.bbappend: synchronize dependencies with upstream recipe
salt.bbappend: synchronize dependencies with upstream recipe

We used to override the upstram dependencies entirely in our bbappend
and that caused divergence with upstream:
1. Some dependencies were duplicated like python, python-futures
2. Some dependencies were present only upstream like python-requests
3. Some dependencies were (and still are) present only in our bbappend

Extend the RDEPENDS variables of the upstream recipe instead of
overwriting it to avoid problems 1 and 2.

Problem 3 is still and issue and will be solved when bumping the
upstream recipe from 2017.7 to 2018.3.

Signed-off-by: Ioan-Adrian Ratiu <7ec73abcfe099fc5574c01312b62768070c80980@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt