Merge pull request #79 from D4N/fix_76

Fixed wrong brackets: size*count + pad can overflow before the cast

src/bigtiffimage.cpp

@@ -227,7 +227,7 @@ namespace Exiv2
                                                   : 1;
 
                 			// #55 memory allocation crash test/data/POC8
-                			long long allocate = (long long) (size*count + pad);
+                			long long allocate = (long long) size*count + pad;
                 			if ( allocate > (long long) io.size() ) {
                     			throw Error(57);
                 			}

src/image.cpp

@@ -402,7 +402,7 @@ namespace Exiv2 {
                 // if ( offset > io.size() ) offset = 0; // Denial of service?
 
                 // #55 memory allocation crash test/data/POC8
-                long long allocate = (long long) (size*count + pad+20);
+                long long allocate = (long long) size*count + pad+20;
                 if ( allocate > (long long) io.size() ) {
                     throw Error(57);
                 }