gstreamer1: fix riscv64 compile

gstreamer1: fix riscv64 compile

Add upstream patch [1]:

  gstconfig.h.in: initial RISC-V support

Fixes [2]:

  ../gst/gstconfig.h:112:4: error: #error "Could not detect architecture; don't know whether it supports unaligned access! Please file a bug."

[1] https://gitlab.freedesktop.org/gstreamer/gstreamer/commit/8a156d1725ecd03f2e8cdc8874e081dda2d3b43d
[2] http://autobuild.buildroot.net/results/07efafadff75ae2fb1d2b8d420be72345906af6c

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>