Fix unwanted sign-extention when converting byte -> int

byte(255) converts to int(-1). This is not what we want, we want
int(255), in other words unsigned conversion.

This bug is causing premature EOF when read() is called, because when a
byte(255) is returned, it gets sign-extend to int(-1), causing the
caller to think EOF is reached.

Bug: 217427392
Test: Presubmit
Change-Id: I8ee864816c77cfe2900f5e300d7d4411cce6753a

packages/DynamicSystemInstallationService/src/com/android/dynsystem/SparseInputStream.java

@@ -177,7 +177,7 @@ public class SparseInputStream extends InputStream {
                 ret = 0;
                 break;
             case SparseChunk.FILL:
-                ret = mCur.fill[(4 - ((int) mLeft & 0x3)) & 0x3];
+                ret = Byte.toUnsignedInt(mCur.fill[(4 - ((int) mLeft & 0x3)) & 0x3]);
                 break;
             default:
                 throw new IOException("Unsupported Chunk:" + mCur.toString());