md5_utils.c: make a function static
md5_utils.c: make a function static

silences a missing prototype warning

Change-Id: I982c9c70e0e9f94a5201559300cadb8bd22441f9

felipebetancur/libvpx,webmproject/libvpx,goodleixiao/vpx,shacklettbp/aom,GrokImageCompression/aom,VTCSecureLLC/libvpx,shacklettbp/aom,Topopiccione/libvpx,stewnorriss/libvpx,webmproject/libvpx,felipebetancur/libvpx,stewnorriss/libvpx,Topopiccione/libvpx,running770/libvpx,luctrudeau/aom,felipebetancur/libvpx,running770/libvpx,running770/libvpx,GrokImageCompression/aom,mbebenita/aom,zofuthan/libvpx,zofuthan/libvpx,luctrudeau/aom,mwgoldsmith/vpx,running770/libvpx,GrokImageCompression/aom,luctrudeau/aom,mwgoldsmith/vpx,mbebenita/aom,shacklettbp/aom,goodleixiao/vpx,jmvalin/aom,liqianggao/libvpx,Topopiccione/libvpx,jmvalin/aom,jmvalin/aom,goodleixiao/vpx,mwgoldsmith/libvpx,shyamalschandra/libvpx,smarter/aom,mwgoldsmith/libvpx,jmvalin/aom,thdav/aom,goodleixiao/vpx,shacklettbp/aom,ShiftMediaProject/libvpx,smarter/aom,shyamalschandra/libvpx,ittiamvpx/libvpx-1,webmproject/libvpx,openpeer/libvpx_new,mwgoldsmith/vpx,stewnorriss/libvpx,running770/libvpx,GrokImageCompression/aom,liqianggao/libvpx,liqianggao/libvpx,jmvalin/aom,ShiftMediaProject/libvpx,shacklettbp/aom,zofuthan/libvpx,VTCSecureLLC/libvpx,goodleixiao/vpx,webmproject/libvpx,zofuthan/libvpx,mbebenita/aom,shyamalschandra/libvpx,smarter/aom,mwgoldsmith/libvpx,Topopiccione/libvpx,GrokImageCompression/aom,thdav/aom,felipebetancur/libvpx,mbebenita/aom,felipebetancur/libvpx,liqianggao/libvpx,thdav/aom,stewnorriss/libvpx,goodleixiao/vpx,smarter/aom,zofuthan/libvpx,shyamalschandra/libvpx,openpeer/libvpx_new,mwgoldsmith/vpx,mbebenita/aom,mwgoldsmith/libvpx,zofuthan/libvpx,liqianggao/libvpx,ittiamvpx/libvpx-1,mbebenita/aom,thdav/aom,mwgoldsmith/libvpx,VTCSecureLLC/libvpx,shyamalschandra/libvpx,webmproject/libvpx,VTCSecureLLC/libvpx,jmvalin/aom,liqianggao/libvpx,openpeer/libvpx_new,ittiamvpx/libvpx-1,Topopiccione/libvpx,luctrudeau/aom,openpeer/libvpx_new,Topopiccione/libvpx,shacklettbp/aom,felipebetancur/libvpx,webmproject/libvpx,mbebenita/aom,GrokImageCompression/aom,mwgoldsmith/vpx,mwgoldsmith/vpx,VTCSecureLLC/libvpx,mbebenita/aom,ShiftMediaProject/libvpx,running770/libvpx,mbebenita/aom,shyamalschandra/libvpx,smarter/aom,smarter/aom,stewnorriss/libvpx,ShiftMediaProject/libvpx,thdav/aom,stewnorriss/libvpx,ShiftMediaProject/libvpx,luctrudeau/aom,mwgoldsmith/libvpx,ittiamvpx/libvpx-1,VTCSecureLLC/libvpx,openpeer/libvpx_new,thdav/aom,ittiamvpx/libvpx-1,ittiamvpx/libvpx-1,openpeer/libvpx_new,luctrudeau/aom