raw: LibRaw_QIODevice::read: fixed possible partial reading of an item

- If the size of an item is greater than 1 byte, it must be ensured that it is not partially read.
- In many readings, LibRAW gives an error if a partial number of items are read so I always try to read everything.

src/imageformats/raw.cpp

@@ -111,10 +111,20 @@ public:
     }
     virtual int read(void *ptr, size_t sz, size_t nmemb) override
     {
-        auto read = m_device->read(reinterpret_cast<char *>(ptr), sz * nmemb);
-        if (read < 1) {
+        qint64 read = 0;
+        if (sz == 0) {
             return 0;
         }
+        auto data = reinterpret_cast<char*>(ptr);
+        for (qint64 r = 0, size = sz * nmemb; read < size; read += r) {
+            if (m_device->atEnd()) {
+                break;
+            }
+            r = m_device->read(data + read, size - read);
+            if (r < 1) {
+                break;
+            }
+        }
         return read / sz;
     }
     virtual int eof() override