testimage: avoid symlinking missing qemu boot log

When qemu test runs only produce suffixed bootlog variants, the base
bootlog path may not exist. os.symlink() creates a dangling symlink
in the oeqa result log directory.

Avoid advertising a boot log in the collected test results when that
path does not exist. Guard the symlink creation and log a note instead.

This is a partial backport of master commit
7a6596925cb0eb8dd48a0362a51875cdd60152bc. Only the symlink guard is
picked here; the bootlog variant globbing from master is not applicable
to scarthgap.

(From OE-Core rev: 6672769e251ab0dd42fc5f5cde99800ed5ba8289)

Signed-off-by: Peter Tatrai <peter.tatrai.ext@siemens.com>
Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
Signed-off-by: Paul Barker <paul@pbarker.dev>

meta/classes-recipe/testimage.bbclass

@@ -395,7 +395,10 @@ def testimage_main(d):
     # Copy additional logs to tmp/log/oeqa so it's easier to find them
     targetdir = os.path.join(get_json_result_dir(d), d.getVar("PN"))
     os.makedirs(targetdir, exist_ok=True)
-    os.symlink(bootlog, os.path.join(targetdir, os.path.basename(bootlog)))
+    if os.path.exists(bootlog):
+        os.symlink(bootlog, os.path.join(targetdir, os.path.basename(bootlog)))
+    else:
+        bb.note("testimage: boot log not found at %s" % bootlog)
     os.symlink(d.getVar("BB_LOGFILE"), os.path.join(targetdir, os.path.basename(d.getVar("BB_LOGFILE") + "." + d.getVar('DATETIME'))))
 
     if not results or not complete: