And free data with the correct free() function in the receive callback
by passing it to gst_buffer_new_wrapped_full() instead of
gst_buffer_new_wrapped().
By passing NULL to `g_signal_new` instead of a marshaller, GLib will
actually internally optimize the signal (if the marshaller is available
in GLib itself) by also setting the valist marshaller. This makes the
signal emission a bit more performant than the regular marshalling,
which still needs to box into `GValue` and call libffi in case of a
generic marshaller.
Note that for custom marshallers, one would use
`g_signal_set_va_marshaller()` with the valist marshaller instead.
On Windows, if libusrsctp and gstreamer are built with different
C runtimes (CRT), we cannot free memory allocated inside libusrsctp
with the `free()` function from gstreamer's CRT.
`usrsctp_freedumpbuffer()` simply calls `free()`, but because of the
way DLLs work on Windows, it will always call the free function from
the correct CRT.
This change makes it possible to create more than just 5 webrtc
data channels. The maximum number of data channels is exactly
DEFAULT_NUMBER_OF_SCTP_STREAMS / 2, therefore the limit is now
512.
