MTP: Check for null string before calling GetStringUTFChars() in MtpDatabase JNI
MTP: Check for null string before calling GetStringUTFChars() in MtpDatabase JNI

BUG: 3274649

Change-Id: I5a3c8fcebf71ed453a121ca5a1345e39895d3bf3
Signed-off-by: Mike Lockwood <368d0007e4626f70737d16df5e49ed8806b98c3f@android.com>

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