Fix MinGW toolchain detection
Fix MinGW toolchain detection

Updated the comment in change I6bef2ab5, but missed adding the code to
the commit.

Change-Id: I14d300489b79730e3995175bfe5f9271b569abe3

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