fix vulnerability in bspatch

Patches with control data tuples with negative numbers in the first
and/or second can cause bspatch to write to arbitrary locations in the
heap.

Change-Id: I8c5d81948be773e6483241131d3d166b6da27cb8
exit instead of return if sideload file creation fails

A return here leaves adb sideload in a permanent loop. An exit is
more appropriate for this error.

Change-Id: I80fb8abae4f6378833aa75f9eaf7ec1acd44b274
Signed-off-by: Ethan Yonker <ethanayonker@gmail.com>