resdl-download.txt: fix cert checking

An APK might posess a MANIFEST.MF but still not have a signature.
It's better to just check for an RSA file.

conf/resdl-download.txt

@@ -164,7 +164,7 @@ verifycerts() {
   for object in $(echo "$stuff_download" | grep -E "^[ ]*[^ ]+.apk[ ]+" | select_word 1); do
     [ -f "$resdldir/$object" ] || continue;
     certobject="$(dirname "$object")/$(basename "$object" .apk).cer";
-    unzip -l "$resdldir/$object" "META-INF/*" | grep -q "META-INF/MANIFEST.MF" && jarsigner -verify "$resdldir/$object" > /dev/null || {
+    unzip -l "$resdldir/$object" "META-INF/*" | grep -q "META-INF/.*.RSA" && jarsigner -verify "$resdldir/$object" > /dev/null || {
       echo "  !! Verification failed for APK ($object)";
       continue;
     }