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

core/java/com/android/internal/os/BatteryStatsImpl.java

@@ -4563,7 +4563,7 @@ public final class BatteryStatsImpl extends BatteryStats {
         mHistory = mHistoryEnd = mHistoryCache = null;
         mHistoryBaseTime = 0;
         long time;
-        while ((time=in.readLong()) >= 0) {
+        while (in.dataAvail() > 0 && (time=in.readLong()) >= 0) {
             HistoryItem rec = new HistoryItem(time, in);
             addHistoryRecordLocked(rec);
             if (rec.time > mHistoryBaseTime) {