Fix some issues flagged by Coverity static analysis

android/src/com/google/zxing/client/android/encode/EncodeActivity.java

@@ -146,7 +146,10 @@ public final class EncodeActivity extends Activity {
       return;
     }
     File barcodeFile = new File(barcodesRoot, makeBarcodeFileName(contents) + ".png");
-    barcodeFile.delete();
+    if (!barcodeFile.delete()) {
+      Log.w(TAG, "Could not delete " + barcodeFile);
+      // continue anyway
+    }
     FileOutputStream fos = null;
     try {
       fos = new FileOutputStream(barcodeFile);

android/src/com/google/zxing/client/android/result/supplement/SupplementalInfoRetriever.java

@@ -55,8 +55,7 @@ public abstract class SupplementalInfoRetriever extends AsyncTask<Object,Object,
     } else if (result instanceof ProductParsedResult) {
       ProductParsedResult productParsedResult = (ProductParsedResult) result;
       String productID = productParsedResult.getProductID();
-      String normalizedProductID = productParsedResult.getNormalizedProductID();
-      SupplementalInfoRetriever productRetriever = 
+      SupplementalInfoRetriever productRetriever =
           new ProductResultInfoRetriever(textView, productID, historyManager, context);
       productRetriever.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
     } else if (result instanceof ISBNParsedResult) {

core/src/main/java/com/google/zxing/maxicode/decoder/DecodedBitStreamParser.java

@@ -98,6 +98,9 @@ final class DecodedBitStreamParser {
   }
 
   private static int getInt(byte[] bytes, byte[] x) {
+    if (x.length == 0) {
+      throw new IllegalArgumentException();
+    }
     int val = 0;
     for (int i = 0; i < x.length; i++) {
       val += getBit(x[i], bytes) << (x.length - i - 1);

core/src/main/java/com/google/zxing/qrcode/encoder/MatrixUtil.java

@@ -305,6 +305,9 @@ final class MatrixUtil {
   // Since all coefficients in the polynomials are 1 or 0, we can do the calculation by bit
   // operations. We don't care if cofficients are positive or negative.
   static int calculateBCHCode(int value, int poly) {
+    if (poly == 0) {
+      throw new IllegalArgumentException("0 polynomial");
+    }
     // If poly is "1 1111 0010 0101" (version info poly), msbSetInPoly is 13. We'll subtract 1
     // from 13 to make it 12.
     int msbSetInPoly = findMSBSet(poly);