Range check in MediaScanner::processDirectory
Range check in MediaScanner::processDirectory

Make sure we don't have an empty string before checking if it's a
directory since this string is tainted.

Change-Id: I5eb310ced58c3c64a7af2d11b80326efe5adbcab

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base