Linux/MacOSX: Read at least 32 bytes from /dev/random before allowing it to fail gracefully

src/Core/RandomNumberGenerator.h

@@ -56,6 +56,7 @@ namespace VeraCrypt
 		static size_t WriteOffset;
 		static struct rand_data *JitterRngCtx;
 		static bool DevRandomSucceeded;
+		static int DevRandomBytesCount;
 	};
 }