runqemu: Also specialcase resolution of '.' to the file's location

Similarly to handling "../", handle "." to resovle to the qemuconf
file's current directory.

(From OE-Core rev: 33418ed064fe9cff5b4803f09135a81d9170c189)

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

scripts/runqemu

@@ -728,6 +728,8 @@ class BaseConfig(object):
             k_upper = k.upper()
             if v.startswith("../"):
                 v = os.path.abspath(os.path.dirname(self.qemuboot) + "/" + v)
+            elif v == ".":
+                v = os.path.dirname(self.qemuboot)
             self.set(k_upper, v)
 
     def validate_paths(self):