testimage.bbclass, lib/oeqa/utils/qemurunner.py: make boot timeout configurable and increase it

On a loaded host (such as an AB setup where multiple builds run)
the 200 seconds timeout might not be enough to reach the login prompt.
Also make it configurable so we can set it from local.conf/auto.conf

(From OE-Core rev: e828571683333e6f18ed56a84e114b5e54975bc7)

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

meta/classes/testimage.bbclass

@@ -7,6 +7,8 @@ DEFAULT_TEST_SUITES_pn-core-image-sato-sdk = "ping ssh connman rpm smart gcc xor
 
 TEST_SUITES ?= "${DEFAULT_TEST_SUITES}"
 
+TEST_QEMUBOOT_TIMEOUT ?= "500"
+
 python do_testimage() {
     testimage_main(d)
 }
@@ -65,6 +67,10 @@ def testimage_main(d):
     qemu.tmpdir = d.getVar("TMPDIR", True)
     qemu.display = d.getVar("BB_ORIGENV", False).getVar("DISPLAY", True)
     qemu.logfile = os.path.join(testdir, "qemu_boot_log.%s" % d.getVar('DATETIME', True))
+    try:
+        qemu.boottime = int(d.getVar("TEST_QEMUBOOT_TIMEOUT", True))
+    except ValueError:
+        qemu.boottime = 500
 
     bb.note("DISPLAY value: %s" % qemu.display)
     bb.note("rootfs file: %s" %  rootfs)