utility-tasks: Set T to alternate location during do_clean

There is a race where do_clean tries to clean WORKDIR but there are logfiles
written into ${T} by bitbake and this can lead to exceptions due to open files.

The easiest solution is to redirect T to a different location for the do_clean
task, hence avoiding the errors and also allowing the logfiles to be visible
somewhere. ${LOG_DIR} seems an appropriate place for this.

[YOCTO #2846]

(From OE-Core rev: eef9d6c2d52f5264a6e7a9d882f8323f9793fd7f)

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

meta/classes/utility-tasks.bbclass

@@ -12,6 +12,7 @@ python do_listtasks() {
 
 CLEANFUNCS ?= ""
 
+T_task-clean = "${LOG_DIR}/cleanlogs/${PN}"
 addtask clean
 do_clean[nostamp] = "1"
 python do_clean() {