bitbake: data: Evaluate the value of export/unexport/network flags

Currently the export/unexport/network flags are acted on only by presence
or lack of in the data store. This is deliberate due to performance reasons
since a given recipe shell task might export ~80-90 variables and this means
expanding flags for every one of them.

This does catch users unaware since values which expand to nothing don't work
e.g. ${@""} and setting values to "0" wouldn't work either.

The downside to this patch is slow down in parsing speed of around 4%.

The network flag is easier to change and doesn't affect performance, it was
made to operate the same as export/unexport for consitency reasons.

(Bitbake rev: 3d96c07f9fd4ba1a84826811d14bb4e98ad58846)

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

bitbake/bin/bitbake-worker

@@ -269,7 +269,7 @@ def fork_off_task(cfg, data, databuilder, workerdata, extraconfigdata, runtask):
 
                 bb.utils.set_process_name("%s:%s" % (the_data.getVar("PN"), taskname.replace("do_", "")))
 
-                if not the_data.getVarFlag(taskname, 'network', False):
+                if not bb.utils.to_boolean(the_data.getVarFlag(taskname, 'network')):
                     if bb.utils.is_local_uid(uid):
                         logger.debug("Attempting to disable network for %s" % taskname)
                         bb.utils.disable_network(uid, gid)