package/gstreamer1/gst1-plugins-bad: add sctp option

package/gstreamer1/gst1-plugins-bad: add sctp option

sctp unconditionnally uses __sync_*_4 intrinsics in
https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/blob/master/ext/sctp/usrsctp/usrsctplib/user_atomic.h

As a result, this will raise the following build failure with bootlin
sparc toolchain:

/srv/storage/autobuild/run/instance-3/output-1/host/opt/ext-toolchain/bin/../lib/gcc/sparc-buildroot-linux-uclibc/9.3.0/../../../../sparc-buildroot-linux-uclibc/bin/ld: ext/sctp/usrsctp/libusrsctp-static.a(usrsctplib_user_socket.c.o): in function `usrsctp_conninput':
user_socket.c:(.text+0x3004): undefined reference to `__sync_fetch_and_add_4'

sctp uses an internal version of usrsctp (which is not available in
buildroot) and is available since version 1.15.1:
https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/commit/e2f06326eac7c3c7fa9c0d5baf4bf9673fc93376

Fixes:
 - http://autobuild.buildroot.org/results/981b11ae9746d1eef40c1797398c4f6c16f005bd

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>