add empty header for backwards compatibility. BUG=none TESTED=lint passes
add empty header for backwards compatibility.
BUG=none
TESTED=lint passes

Review URL: https://webrtc-codereview.appspot.com/46919004
zpc930/libyuv,swak/libyuv,FAHADSUST/libyuv,danilogr/libyuv,happy-star/libyuv,Malek44/libyuv,gengchenglin/libyuv,virneo/libyuv,nanguantong/libyuv,JuannyWang/libyuv,ddpatel2606/libyuv,codyc/libyuv,koxiong/libyuv,dong83615/libyuv,jrdeng/libyuv,foolab/libyuv,JuannyWang/libyuv,envyen/libyuv,zijay0822/libyuv,swak/libyuv,dreamcoder/libyuv,sepcity/libyuv,Shamim1977/libyuv,sateeshyegireddi/libyuv,Locnath/libyuv,skyofdwarf/libyuv,dreamcoder/libyuv,swak/libyuv,torodavit/libyuv,zpc930/libyuv,stephenyin/libyuv,se7en3rd/libyuv,stephenyin/libyuv,gengchenglin/libyuv,skyofdwarf/libyuv,huangxueqin/libyuv,dong83615/libyuv,drybeans/libyuv,codyc/libyuv,ksophocleous/libyuv,Malek44/libyuv,lemoon/libyuv,buliaoyin/libyuv,ddpatel2606/libyuv,gavinljj/libyuv,muslim1977/libyuv,todostreaming/libyuv,wmiller848/libyuv,kiwifig/libyuv,alfatraining/libyuv,bluceldg/libyuv,theunreplicated/libyuv,torodavit/libyuv,eterrao/libyuv,biotrump/libyuv,lcwyylcwyy/libyuv,wanggenggz/libyuv,xiongdaofu/libyuv,andriy-yermakov/libyuv,bluceldg/libyuv,ksophocleous/libyuv,gengchenglin/libyuv,gavinljj/libyuv,zothen/libyuv,hongqingquan/libyuv,jhanay/libyuv,leetaizhu/libyuv,lemoon/libyuv,AshwanthSelvam/libyuv,kpgalligan/libyuv,pecoco/libyuv,cjr1983/libyuv,wow2006/libyuv,sepcity/libyuv,ericma2014/libyuv,todostreaming/libyuv,sateeshyegireddi/libyuv,envyen/libyuv,leetaizhu/libyuv,ericma2014/libyuv,eterrao/libyuv,polyzz/libyuv,Padmassri/libyuv,weifud/libyuv,wow2006/libyuv,EdgarMora/libyuv,sateeshyegireddi/libyuv,patrickcusack/libyuv,danilogr/libyuv,pecoco/libyuv,Ariesnix/libyuv,jrdeng/libyuv,sitoumbaz/libyuv,leeslove/libyuv,wow2006/libyuv,kpgalligan/libyuv,andriy-yermakov/libyuv,binsys/libyuv,theunreplicated/libyuv,KIHOSONG/libyuv,pecoco/libyuv,fjyihan/libyuv,zhuolinho/libyuv,Miliox/libyuv,wanggenggz/libyuv,alfatraining/libyuv,jeyluta/libyuv,elkpi/libyuv,mayurAzoi/libyuv,liuzhe02/libyuv,polyzz/libyuv,stephenyin/libyuv,mayurAzoi/libyuv,zhuolinho/libyuv,xcl010/libyuv,changchang/libyuv,sigysmund/libyuv,sitoumbaz/libyuv,wanggenggz/libyuv,se7en3rd/libyuv,elkpi/libyuv,liuzhe02/libyuv,happy-star/libyuv,zj2089/libyuv,Ariesnix/libyuv,polyzz/libyuv,Padmassri/libyuv,buliaoyin/libyuv,ksophocleous/libyuv,binsys/libyuv,heyfluke/libyuv,happy-star/libyuv,xuruhao/libyuv,BigMing001/libyuv,leeslove/libyuv,FAHADSUST/libyuv,EdgarMora/libyuv,mannuray/libyuv,FAHADSUST/libyuv,ericma2014/libyuv,Locnath/libyuv,BigMing001/libyuv,virneo/libyuv,biotrump/libyuv,weifud/libyuv,Eikan/libyuv,zijay0822/libyuv,kpgalligan/libyuv,Evgeniy-Odesskiy/libyuv,jeyluta/libyuv,drybeans/libyuv,platoon-code/libyuv,todostreaming/libyuv,mannuray/libyuv,danilogr/libyuv,bluceldg/libyuv,Evgeniy-Odesskiy/libyuv,mayurAzoi/libyuv,lyx2014/libyuv,Evgeniy-Odesskiy/libyuv,gavinljj/libyuv,walletiger/libyuv,alfatraining/libyuv,zothen/libyuv,sigysmund/libyuv,BigMing001/libyuv,tectronics/libyuv,Malek44/libyuv,elkpi/libyuv,zj2089/libyuv,zephyroal/libyuv,yosoymin/libyuv,theunreplicated/libyuv,changchang/libyuv,walletiger/libyuv,zpc930/libyuv,jhanay/libyuv,wmiller848/libyuv,torodavit/libyuv,AshwanthSelvam/libyuv,hushuitian/libyuv,yosoymin/libyuv,dong83615/libyuv,jhanay/libyuv,drybeans/libyuv,fjyihan/libyuv,walletiger/libyuv,tectronics/libyuv,envyen/libyuv,oiramario/libyuv,huangxueqin/libyuv,lyx2014/libyuv,xcl010/libyuv,muslim1977/libyuv,cjr1983/libyuv,oiramario/libyuv,fjyihan/libyuv,Locnath/libyuv,dreamcoder/libyuv,lemoon/libyuv,AshwanthSelvam/libyuv,andriy-yermakov/libyuv,yosoymin/libyuv,sepcity/libyuv,Eikan/libyuv,zj2089/libyuv,xiongdaofu/libyuv,alfatraining/libyuv,buliaoyin/libyuv,hongqingquan/libyuv,patrickcusack/libyuv,ddpatel2606/libyuv,nanguantong/libyuv,huangxueqin/libyuv,EdgarMora/libyuv,Eikan/libyuv,kiwifig/libyuv,KIHOSONG/libyuv,muslim1977/libyuv,zijay0822/libyuv,hushuitian/libyuv,Ariesnix/libyuv,jeyluta/libyuv,patrickcusack/libyuv,kiwifig/libyuv,skyofdwarf/libyuv,Padmassri/libyuv,foolab/libyuv,sitoumbaz/libyuv,platoon-code/libyuv,xuruhao/libyuv,hushuitian/libyuv,xiongdaofu/libyuv,nanguantong/libyuv,heyfluke/libyuv,Miliox/libyuv,katepanping/libyuv,codyc/libyuv,zephyroal/libyuv,koxiong/libyuv,KIHOSONG/libyuv,platoon-code/libyuv,wmiller848/libyuv,lcwyylcwyy/libyuv,hongqingquan/libyuv,Shamim1977/libyuv,katepanping/libyuv,foolab/libyuv,biotrump/libyuv,binsys/libyuv,xuruhao/libyuv,xcl010/libyuv,zhuolinho/libyuv,liuzhe02/libyuv,eterrao/libyuv,changchang/libyuv,lcwyylcwyy/libyuv,jrdeng/libyuv,mannuray/libyuv,Shamim1977/libyuv,sigysmund/libyuv,cjr1983/libyuv,weifud/libyuv,oiramario/libyuv,zothen/libyuv,leeslove/libyuv,Miliox/libyuv,virneo/libyuv,koxiong/libyuv,tectronics/libyuv,leetaizhu/libyuv,katepanping/libyuv,lyx2014/libyuv,se7en3rd/libyuv,zephyroal/libyuv,heyfluke/libyuv,JuannyWang/libyuv