Fix parallel install
Fix parallel install

Require the destination to be present before trying to create the symlink.
See: http://bugs.gentoo.org/show_bug.cgi?id=323805

Change-Id: I14ed4a9792dedc289885a9a43bc5a86cb792206d

luctrudeau/aom,running770/libvpx,shacklettbp/aom,turbulenz/libvpx,shareefalis/libvpx,running770/libvpx,jdm/libvpx,gshORTON/webm.libvpx,Acidburn0zzz/webm.libvpx,mbebenita/aom,kalli123/webm.libvpx,WebRTC-Labs/libvpx,ittiamvpx/libvpx-1,GrokImageCompression/aom,lyx2014/libvpx_c,sanyaade-teachings/libvpx,shareefalis/libvpx,Maria1099/webm.libvpx,luctrudeau/aom,liqianggao/libvpx,ittiamvpx/libvpx,smarter/aom,cinema6/libvpx,mwgoldsmith/libvpx,zofuthan/libvpx,webmproject/libvpx,luctrudeau/aom,kalli123/webm.libvpx,ittiamvpx/libvpx-1,matanbs/webm.libvpx,VTCSecureLLC/libvpx,stewnorriss/libvpx,Laknot/libvpx,Distrotech/libvpx,openpeer/libvpx_new,altogother/webm.libvpx,mbebenita/aom,felipebetancur/libvpx,stewnorriss/libvpx,reimaginemedia/webm.libvpx,webmproject/libvpx,lyx2014/libvpx_c,vasilvv/esvp8,iniwf/webm.libvpx,openpeer/libvpx_new,reimaginemedia/webm.libvpx,mbebenita/aom,liqianggao/libvpx,hsueceumd/test_hui,thdav/aom,shyamalschandra/libvpx,sanyaade-teachings/libvpx,matanbs/vp982,jacklicn/webm.libvpx,zofuthan/libvpx,ittiamvpx/libvpx,Maria1099/webm.libvpx,hsueceumd/test_hui,thdav/aom,jdm/libvpx,abwiz0086/webm.libvpx,turbulenz/libvpx,Suvarna1488/webm.libvpx,reimaginemedia/webm.libvpx,matanbs/vp982,matanbs/vp982,ittiamvpx/libvpx-1,ShiftMediaProject/libvpx,VTCSecureLLC/libvpx,mbebenita/aom,stewnorriss/libvpx,goodleixiao/vpx,kim42083/webm.libvpx,charup/https---github.com-webmproject-libvpx-,smarter/aom,altogother/webm.libvpx,iniwf/webm.libvpx,kim42083/webm.libvpx,pcwalton/libvpx,stewnorriss/libvpx,awatry/libvpx.opencl,charup/https---github.com-webmproject-libvpx-,charup/https---github.com-webmproject-libvpx-,kleopatra999/webm.libvpx,GrokImageCompression/aom,pcwalton/libvpx,jmvalin/aom,smarter/aom,Maria1099/webm.libvpx,Laknot/libvpx,thdav/aom,altogother/webm.libvpx,GrokImageCompression/aom,n4t/libvpx,mbebenita/aom,mwgoldsmith/vpx,Topopiccione/libvpx,vasilvv/esvp8,reimaginemedia/webm.libvpx,shyamalschandra/libvpx,ittiamvpx/libvpx,mwgoldsmith/libvpx,goodleixiao/vpx,stewnorriss/libvpx,thdav/aom,genesi/libvpx0,hsueceumd/test_hui,gshORTON/webm.libvpx,Maria1099/webm.libvpx,thdav/aom,jacklicn/webm.libvpx,matanbs/vp982,mwgoldsmith/vpx,liqianggao/libvpx,VTCSecureLLC/libvpx,reimaginemedia/webm.libvpx,turbulenz/libvpx,sanyaade-teachings/libvpx,hsueceumd/test_hui,shyamalschandra/libvpx,awatry/libvpx.opencl,cinema6/libvpx,rikaunite/gst-opera_libvpx,Topopiccione/libvpx,Maria1099/webm.libvpx,turbulenz/libvpx,lyx2014/libvpx_c,kim42083/webm.libvpx,mbebenita/aom,Distrotech/libvpx,hsueceumd/test_hui,jdm/libvpx,Acidburn0zzz/webm.libvpx,pcwalton/libvpx,kim42083/webm.libvpx,shareefalis/libvpx,jdm/libvpx,liqianggao/libvpx,felipebetancur/libvpx,Acidburn0zzz/webm.libvpx,enmasse-entertainment/libvpx,ShiftMediaProject/libvpx,zofuthan/libvpx,jacklicn/webm.libvpx,cinema6/libvpx,zofuthan/libvpx,felipebetancur/libvpx,charup/https---github.com-webmproject-libvpx-,GrokImageCompression/aom,n4t/libvpx,Laknot/libvpx,Acidburn0zzz/webm.libvpx,kim42083/webm.libvpx,kalli123/webm.libvpx,openpeer/libvpx_new,mbebenita/aom,kleopatra999/webm.libvpx,awatry/libvpx.opencl,genesi/libvpx0,enmasse-entertainment/libvpx,kleopatra999/webm.libvpx,sanyaade-teachings/libvpx,altogother/webm.libvpx,enmasse-entertainment/libvpx,gshORTON/webm.libvpx,felipebetancur/libvpx,goodleixiao/vpx,cinema6/libvpx,ShiftMediaProject/libvpx,Distrotech/libvpx,kalli123/webm.libvpx,shareefalis/libvpx,kleopatra999/webm.libvpx,Maria1099/webm.libvpx,WebRTC-Labs/libvpx,iniwf/webm.libvpx,vasilvv/esvp8,running770/libvpx,luctrudeau/aom,Suvarna1488/webm.libvpx,mbebenita/aom,kleopatra999/webm.libvpx,jmvalin/aom,Topopiccione/libvpx,jmvalin/aom,ShiftMediaProject/libvpx,Laknot/libvpx,altogother/webm.libvpx,rikaunite/gst-opera_libvpx,smarter/aom,ShiftMediaProject/libvpx,jmvalin/aom,iniwf/webm.libvpx,genesi/libvpx0,Acidburn0zzz/webm.libvpx,goodleixiao/vpx,lyx2014/libvpx_c,Topopiccione/libvpx,pcwalton/libvpx,ittiamvpx/libvpx,running770/libvpx,rikaunite/gst-opera_libvpx,vasilvv/esvp8,Distrotech/libvpx,mwgoldsmith/libvpx,openpeer/libvpx_new,vasilvv/esvp8,mwgoldsmith/libvpx,matanbs/vp982,running770/libvpx,webmproject/libvpx,Suvarna1488/webm.libvpx,openpeer/libvpx_new,abwiz0086/webm.libvpx,hsueceumd/test_hui,abwiz0086/webm.libvpx,matanbs/webm.libvpx,Suvarna1488/webm.libvpx,enmasse-entertainment/libvpx,iniwf/webm.libvpx,turbulenz/libvpx,kleopatra999/webm.libvpx,mwgoldsmith/libvpx,jmvalin/aom,shacklettbp/aom,genesi/libvpx0,shacklettbp/aom,running770/libvpx,GrokImageCompression/aom,pcwalton/libvpx,matanbs/webm.libvpx,goodleixiao/vpx,genesi/libvpx0,luctrudeau/aom,liqianggao/libvpx,matanbs/webm.libvpx,Laknot/libvpx,webmproject/libvpx,gshORTON/webm.libvpx,felipebetancur/libvpx,reimaginemedia/webm.libvpx,shyamalschandra/libvpx,gshORTON/webm.libvpx,Laknot/libvpx,cinema6/libvpx,turbulenz/libvpx,shyamalschandra/libvpx,liqianggao/libvpx,smarter/aom,rikaunite/gst-opera_libvpx,matanbs/webm.libvpx,mwgoldsmith/vpx,zofuthan/libvpx,jacklicn/webm.libvpx,goodleixiao/vpx,matanbs/vp982,webmproject/libvpx,openpeer/libvpx_new,WebRTC-Labs/libvp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