selftests: forwarding: Remove duplicated lib.sh content

commit 25ae948b44 ("selftests/net: add lib.sh") added net/lib.sh to
contain code shared by tests under net/ and net/forwarding/. However, this
caused issues with selftests from directories other than net/forwarding/,
in particular those under drivers/net/. Those issues were avoided in a
simple way by duplicating some content in commit 2114e83381 ("selftests:
forwarding: Avoid failures to source net/lib.sh").

In order to remove the duplicated content, restore the inclusion of
net/lib.sh from net/forwarding/lib.sh but with the following changes:

* net/lib.sh is imported through the net_forwarding_dir path
The original expression "source ../lib.sh" would look for lib.sh in the
directory above the script file's one, which did not work for tests under
drivers/net/.

* net/lib.sh is added to TEST_INCLUDES
Since net/forwarding/lib.sh now sources net/lib.sh, both of those files
must be exported along with tests which source net/forwarding/lib.sh.

Suggested-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Benjamin Poirier <bpoirier@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/forwarding/lib.sh

@@ -35,31 +35,7 @@ if [[ -f $net_forwarding_dir/forwarding.config ]]; then
 	source "$net_forwarding_dir/forwarding.config"
 fi
 
-# Kselftest framework requirement - SKIP code is 4.
-ksft_skip=4
-
-busywait()
-{
-	local timeout=$1; shift
-
-	local start_time="$(date -u +%s%3N)"
-	while true
-	do
-		local out
-		out=$("$@")
-		local ret=$?
-		if ((!ret)); then
-			echo -n "$out"
-			return 0
-		fi
-
-		local current_time="$(date -u +%s%3N)"
-		if ((current_time - start_time > timeout)); then
-			echo -n "$out"
-			return 1
-		fi
-	done
-}
+source "$net_forwarding_dir/../lib.sh"
 
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 # Sanity checks