Linux: rethrow exceptions correctly

otherwise exception messages are not kept

Author: letmaik

pyvirtualcam/native_linux_v4l2loopback/virtual_output.h

@@ -130,7 +130,7 @@ class VirtualOutput {
             } catch (std::exception &ex) {
                 close(_camera_fd);
                 _camera_fd = -1;
-                throw ex;
+                throw;
             }
         };