testimage: add task level lock

For machines other than qemu it will not be okay to run
multiple testimage tasks in parallel.

(From OE-Core rev: 9560305a9e28316438cb57421afc7877890c4b76)

Signed-off-by: Stefan Stanacar <stefanx.stanacar@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/testimage-auto.bbclass

@@ -20,3 +20,4 @@ python do_testimage_auto() {
 }
 addtask testimage_auto before do_build after do_rootfs
 do_testimage_auto[depends] += "${TESTIMAGEDEPENDS}"
+do_testimage_auto[lockfiles] += "${TESTIMAGELOCK}"

meta/classes/testimage.bbclass

@@ -42,12 +42,16 @@ TEST_SERVER_IP ?= ""
 TESTIMAGEDEPENDS = ""
 TESTIMAGEDEPENDS_qemuall = "qemu-native:do_populate_sysroot qemu-helper-native:do_populate_sysroot"
 
+TESTIMAGELOCK = "${TMPDIR}/testimage.lock"
+TESTIMAGELOCK_qemuall = ""
+
 python do_testimage() {
     testimage_main(d)
 }
 addtask testimage
 do_testimage[nostamp] = "1"
 do_testimage[depends] += "${TESTIMAGEDEPENDS}"
+do_testimage[lockfiles] += "${TESTIMAGELOCK}"
 
 
 def get_tests_list(d):