Adding a sanity test in the while loop in readHistory()

Adding a sanity test in the while loop in readHistory() which
is useful in case the file read (batterystats.bin), is corrupt.
The file can get corrupt (missing end of file marker -1) if
writeHistory fails for some reason. Without this change
readHistory will continue looping untill an OutOfMemory is
thrown.

Change-Id: I3418d258e7cb99aa2f9d934c9449a19806499ce4
1 file changed