Redact Account info from getCurrentSyncs

BUG:26094635
If the caller to ContentResolver#getCurrentSyncs does not hold the
GET_ACCOUNTS permission, return a SyncInfo object that does not
contain any Account information.

Change-Id: I5628ebe1f56c8e3f784aaf1b3281e6b829d19314
(cherry picked from commit b63057e698a01dafcefc7ba09b397b0336bba43d)
