oe-selftest: fix behaviour if oe-selftest.log is a dangling symlink

If you delete the log file that the oe-selftest.log symlink points to
but not the symlink itself, because we were using os.path.exists() here
the code assumed that the symlink didn't exist when in fact it still
did. Use os.path.lexists() instead.

(From OE-Core rev: 263af91a0efd21e041ecdb0c40f9b2d4e735f67d)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/oe-selftest

@@ -62,7 +62,8 @@ log_prefix = "oe-selftest-" + t.strftime("%Y%m%d-%H%M%S")
 
 def logger_create():
     log_file = log_prefix + ".log"
-    if os.path.exists("oe-selftest.log"): os.remove("oe-selftest.log")
+    if os.path.lexists("oe-selftest.log"):
+        os.remove("oe-selftest.log")
     os.symlink(log_file, "oe-selftest.log")
 
     log = logging.getLogger("selftest")