fix cookie checks for patreon, fanbox, fantia

The changes in 9a255344 caused a warning about missing cookies to be
displayed even if those cookies were present, because _check_cookies()
did not account for an empty cookiedomain.

gallery_dl/extractor/common.py

@@ -336,7 +336,8 @@ class Extractor():
         now = time.time()
 
         for cookie in self._cookiejar:
-            if cookie.name in names and cookie.domain == domain:
+            if cookie.name in names and (
+                    not domain or cookie.domain == domain):
                 if cookie.expires and cookie.expires < now:
                     self.log.warning("Cookie '%s' has expired", cookie.name)
                 else:

gallery_dl/extractor/patreon.py

@@ -20,6 +20,7 @@ class PatreonExtractor(Extractor):
     """Base class for patreon extractors"""
     category = "patreon"
     root = "https://www.patreon.com"
+    cookiedomain = ".patreon.com"
     directory_fmt = ("{category}", "{creator[full_name]}")
     filename_fmt = "{id}_{title}_{num:>02}.{extension}"
     archive_fmt = "{id}_{num}"