partitionmanager: support delayed adopted storage mount

* On some devices, the external mmc driver will only load the card after
  a certain delay. The original code will break and fail to mount any
  adopted storage in this case.

* Add a special fstab flag to allow the partitionmanager to retry after
  a delay.

Change-Id: I219978850ff3ba7ad9dc7ca96fc30634c9574164
diff --git a/partitions.hpp b/partitions.hpp
index 9c2b65f..49ebf60 100755
--- a/partitions.hpp
+++ b/partitions.hpp
@@ -168,6 +168,7 @@
 	string Crypto_Key_Location;                                               // Location of the crypto key used for decrypting encrypted data partitions
 	unsigned int MTP_Storage_ID;
 	string Adopted_GUID;
+	unsigned int Adopted_Mount_Delay;
 	bool Has_Data_Media;                                                      // Indicates presence of /data/media, may affect wiping and backup methods