Removing unused motion_vector_context enum from vp9_encodeframe.c
Removing unused motion_vector_context enum from vp9_encodeframe.c

The same enum defined and used in vp9_mvref_common.c.

Change-Id: I3975103997797add0a258d36c96d20ac9561a73d

Suvarna1488/webm.libvpx,matanbs/vp982,thdav/aom,webmproject/libvpx,gshORTON/webm.libvpx,luctrudeau/aom,hsueceumd/test_hui,Topopiccione/libvpx,jdm/libvpx,stewnorriss/libvpx,stewnorriss/libvpx,GrokImageCompression/aom,ShiftMediaProject/libvpx,GrokImageCompression/aom,mwgoldsmith/vpx,stewnorriss/libvpx,zofuthan/libvpx,jmvalin/aom,lyx2014/libvpx_c,kim42083/webm.libvpx,liqianggao/libvpx,lyx2014/libvpx_c,matanbs/vp982,goodleixiao/vpx,running770/libvpx,shacklettbp/aom,Laknot/libvpx,goodleixiao/vpx,jmvalin/aom,webmproject/libvpx,mwgoldsmith/libvpx,openpeer/libvpx_new,matanbs/vp982,kim42083/webm.libvpx,lyx2014/libvpx_c,felipebetancur/libvpx,ittiamvpx/libvpx-1,GrokImageCompression/aom,VTCSecureLLC/libvpx,reimaginemedia/webm.libvpx,shacklettbp/aom,smarter/aom,smarter/aom,VTCSecureLLC/libvpx,altogother/webm.libvpx,jacklicn/webm.libvpx,shareefalis/libvpx,iniwf/webm.libvpx,charup/https---github.com-webmproject-libvpx-,shacklettbp/aom,shyamalschandra/libvpx,Acidburn0zzz/webm.libvpx,running770/libvpx,zofuthan/libvpx,charup/https---github.com-webmproject-libvpx-,kalli123/webm.libvpx,shareefalis/libvpx,jmvalin/aom,mbebenita/aom,jmvalin/aom,mwgoldsmith/vpx,charup/https---github.com-webmproject-libvpx-,shyamalschandra/libvpx,stewnorriss/libvpx,kim42083/webm.libvpx,shyamalschandra/libvpx,jdm/libvpx,felipebetancur/libvpx,ittiamvpx/libvpx,kleopatra999/webm.libvpx,gshORTON/webm.libvpx,abwiz0086/webm.libvpx,luctrudeau/aom,reimaginemedia/webm.libvpx,kleopatra999/webm.libvpx,running770/libvpx,hsueceumd/test_hui,Maria1099/webm.libvpx,shyamalschandra/libvpx,matanbs/vp982,GrokImageCompression/aom,Acidburn0zzz/webm.libvpx,matanbs/webm.libvpx,ShiftMediaProject/libvpx,kleopatra999/webm.libvpx,VTCSecureLLC/libvpx,shareefalis/libvpx,kalli123/webm.libvpx,Acidburn0zzz/webm.libvpx,pcwalton/libvpx,lyx2014/libvpx_c,mbebenita/aom,thdav/aom,ShiftMediaProject/libvpx,altogother/webm.libvpx,matanbs/webm.libvpx,n4t/libvpx,ittiamvpx/libvpx-1,iniwf/webm.libvpx,thdav/aom,webmproject/libvpx,ittiamvpx/libvpx-1,mbebenita/aom,kalli123/webm.libvpx,matanbs/vp982,stewnorriss/libvpx,altogother/webm.libvpx,luctrudeau/aom,mbebenita/aom,Laknot/libvpx,matanbs/vp982,Suvarna1488/webm.libvpx,shacklettbp/aom,jdm/libvpx,Acidburn0zzz/webm.libvpx,mwgoldsmith/libvpx,lyx2014/libvpx_c,Topopiccione/libvpx,ittiamvpx/libvpx,gshORTON/webm.libvpx,webmproject/libvpx,pcwalton/libvpx,pcwalton/libvpx,hsueceumd/test_hui,abwiz0086/webm.libvpx,VTCSecureLLC/libvpx,mwgoldsmith/vpx,running770/libvpx,thdav/aom,running770/libvpx,reimaginemedia/webm.libvpx,goodleixiao/vpx,jdm/libvpx,gshORTON/webm.libvpx,kalli123/webm.libvpx,mwgoldsmith/vpx,liqianggao/libvpx,luctrudeau/aom,ittiamvpx/libvpx-1,iniwf/webm.libvpx,ittiamvpx/libvpx,openpeer/libvpx_new,pcwalton/libvpx,reimaginemedia/webm.libvpx,Laknot/libvpx,lyx2014/libvpx_c,reimaginemedia/webm.libvpx,mbebenita/aom,mbebenita/aom,felipebetancur/libvpx,running770/libvpx,n4t/libvpx,iniwf/webm.libvpx,shareefalis/libvpx,mwgoldsmith/libvpx,felipebetancur/libvpx,mwgoldsmith/libvpx,ittiamvpx/libvpx,shyamalschandra/libvpx,openpeer/libvpx_new,Topopiccione/libvpx,Acidburn0zzz/webm.libvpx,mwgoldsmith/vpx,zofuthan/libvpx,goodleixiao/vpx,n4t/libvpx,charup/https---github.com-webmproject-libvpx-,Topopiccione/libvpx,matanbs/webm.libvpx,mwgoldsmith/libvpx,gshORTON/webm.libvpx,jdm/libvpx,charup/https---github.com-webmproject-libvpx-,shyamalschandra/libvpx,mwgoldsmith/vpx,jmvalin/aom,Topopiccione/libvpx,Suvarna1488/webm.libvpx,kim42083/webm.libvpx,smarter/aom,gshORTON/webm.libvpx,Distrotech/libvpx,kim42083/webm.libvpx,zofuthan/libvpx,Suvarna1488/webm.libvpx,charup/https---github.com-webmproject-libvpx-,zofuthan/libvpx,shacklettbp/aom,mbebenita/aom,webmproject/libvpx,Laknot/libvpx,mwgoldsmith/libvpx,zofuthan/libvpx,liqianggao/libvpx,jmvalin/aom,ShiftMediaProject/libvpx,thdav/aom,goodleixiao/vpx,jacklicn/webm.libvpx,felipebetancur/libvpx,ittiamvpx/libvpx,Maria1099/webm.libvpx,n4t/libvpx,Maria1099/webm.libvpx,kalli123/webm.libvpx,ShiftMediaProject/libvpx,openpeer/libvpx_new,hsueceumd/test_hui,jacklicn/webm.libvpx,jacklicn/webm.libvpx,mbebenita/aom,liqianggao/libvpx,Maria1099/webm.libvpx,openpeer/libvpx_new,ittiamvpx/libvpx-1,Distrotech/libvpx,hsueceumd/test_hui,hsueceumd/test_hui,abwiz0086/webm.libvpx,shacklettbp/aom,Suvarna1488/webm.libvpx,Suvarna1488/webm.libvpx,VTCSecureLLC/libvpx,abwiz0086/webm.libvpx,goodleixiao/vpx,jdm/libvpx,abwiz0086/webm.libvpx,altogother/webm.libvpx,altogother/webm.libvpx,matanbs/vp982,pcwalton/libvpx,matanbs/webm.libvpx,shareefalis/libvpx,luctrudeau/aom,Acidburn0zzz/webm.libvpx,matanbs/webm.libvpx,Distrotech/libvpx,kim42083/webm.libvpx,ittiamvpx/libvpx-1,stewnorriss/libvpx,matanbs/webm.libvpx,pcwalton/libvpx,jacklicn/webm.libvpx,abwiz0086/webm.libvpx,GrokImageCompression/aom,altogother/webm.libvpx,ittiamvpx/libvpx,Distrotech/libvpx,n4t/libvpx,kleopatra999/webm.libvpx,iniwf/webm.libvpx,luctrudeau/aom,kleopatra999/webm.libvpx,GrokImageCompression/aom,felipebetancur/libvpx,kalli123/webm.libvpx,smarter/aom,Distrotech/libvpx,jacklicn/webm.libvpx,thdav/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