Compiler warnings from (CMake & Meson) build

[eero-t]

After working around build issues #145 & #146 (see them for the setup info), following compiler warnings remain:

In file included from gstreamer-media-sdk/parsers/gstvc1parse.h:26:0,
                 from gstreamer-media-sdk/gst/mfx/gstmfx.c:49:
/usr/include/gstreamer-1.0/gst/codecparsers/gstvc1parser.h:26:2: warning: #warning "The VC1 parsing library is unstable API and may change in future." [-Wcpp]
 #warning "The VC1 parsing library is unstable API and may change in future."
  ^~~~~~~
/usr/include/gstreamer-1.0/gst/codecparsers/gstvc1parser.h:27:2: warning: #warning "You can define GST_USE_UNSTABLE_API to avoid this warning." [-Wcpp]
 #warning "You can define GST_USE_UNSTABLE_API to avoid this warning."
  ^~~~~~~
In file included from gstreamer-media-sdk/gst-libs/mfx/gstmfxutils_h264.c:24:0:
/usr/include/gstreamer-1.0/gst/codecparsers/gsth264parser.h:34:2: warning: #warning "The H.264 parsing library is unstable API and may change in future." [-Wcpp]
 #warning "The H.264 parsing library is unstable API and may change in future."
  ^~~~~~~
/usr/include/gstreamer-1.0/gst/codecparsers/gsth264parser.h:35:2: warning: #warning "You can define GST_USE_UNSTABLE_API to avoid this warning." [-Wcpp]
 #warning "You can define GST_USE_UNSTABLE_API to avoid this warning."
  ^~~~~~~
In file included from /usr/include/glib-2.0/glib.h:62:0,
                 from /usr/include/gstreamer-1.0/gst/gst.h:27,
                 from gstreamer-media-sdk/gst-libs/mfx/sysdeps.h:33,
                 from gstreamer-media-sdk/gst-libs/mfx/gstmfxwindow.c:23:
gstreamer-media-sdk/gst-libs/mfx/gstmfxwindow.c: In function ‘gst_mfx_window_get_handle’:
/usr/include/glib-2.0/glib/gmessages.h:599:10: warning: return makes integer from pointer without a cast [-Wint-conversion]
   return (val);       \
          ^
gstreamer-media-sdk/gst-libs/mfx/gstmfxwindow.c:237:3: note: in expansion of macro ‘g_return_val_if_fail’
   g_return_val_if_fail (window != NULL, NULL);
   ^~~~~~~~~~~~~~~~~~~~
In file included from /opt/builder/source1/gstreamer-media-sdk/gst-libs/mfx/gstmfxdecoder.c:24:0:
/usr/include/gstreamer-1.0/gst/codecparsers/gsth264parser.h:34:2: warning: #warning "The H.264 parsing library is unstable API and may change in future." [-Wcpp]
 #warning "The H.264 parsing library is unstable API and may change in future."
  ^~~~~~~
/usr/include/gstreamer-1.0/gst/codecparsers/gsth264parser.h:35:2: warning: #warning "You can define GST_USE_UNSTABLE_API to avoid this warning." [-Wcpp]
 #warning "You can define GST_USE_UNSTABLE_API to avoid this warning."
  ^~~~~~~
In file included from gstreamer-media-sdk/parsers/gstvc1parse.h:26:0,
                 from gstreamer-media-sdk/parsers/gstvc1parse.c:78:
/usr/include/gstreamer-1.0/gst/codecparsers/gstvc1parser.h:26:2: warning: #warning "The VC1 parsing library is unstable API and may change in future." [-Wcpp]
 #warning "The VC1 parsing library is unstable API and may change in future."
  ^~~~~~~
/usr/include/gstreamer-1.0/gst/codecparsers/gstvc1parser.h:27:2: warning: #warning "You can define GST_USE_UNSTABLE_API to avoid this warning." [-Wcpp]
 #warning "You can define GST_USE_UNSTABLE_API to avoid this warning."
  ^~~~~~~
gstreamer-media-sdk/parsers/gstvc1parse.c:118:3: warning: ‘parse_formats’ defined but not used [-Wunused-const-variable=]
 } parse_formats[] = {
   ^~~~~~~~~~~~~

[eero-t]

Got few additional warnings from similarly configured Meson build (after working around #148):

gst/mfx/gstmfxpluginbase.c:427:23: warning: unused variable ‘params’ [-Wunused-variable]
   const GstStructure *params;
                       ^~~~~~
gst/mfx/gstmfxsink.c: In function ‘x11_keycode_to_keysym’:
gst/mfx/gstmfxsink.c:169:3: warning: ‘XKeycodeToKeysym’ is deprecated [-Wdeprecated-declarations]
   return XKeycodeToKeysym (dpy, kc, 0);
   ^~~~~~
In file included from /opt/install/Custom_4163/include/va/va_x11.h:28:0,
                 from gst-libs/mfx/x11/gstmfxdisplay_x11.h:26,
                 from gst/mfx/gstmfxsink.c:156:
/usr/include/X11/Xlib.h:1687:15: note: declared here
 extern KeySym XKeycodeToKeysym(
               ^~~~~~~~~~~~~~~~