multiple libgif versions support for gif2webp
multiple libgif versions support for gif2webp

Make it work for libgif v5.0+, for which a couple of APIs have changed.

Change-Id: I6dd49bb5bf1b60f96f3a164d58ef2ef19281c96b

abwiz0086/webm.libwebp,kleopatra999/webm.libwebp,matanbs/webm.libwebp,matanbs/webm.libwebp,yohunl/libwebp,ericmckean/webm.libwebp,redengineer/libwebp,gshORTON/webm.libwebp,jacklicn/libwebp,imazen/libwebp,Distrotech/libwebp,jiehu5114/libwebp,keane83/BLE_IM,kleopatra999/webm.libwebp,yohunl/libwebp,ttyangf/libwebp,Acidburn0zzz/webm.libwebp,iniwf/webm.libwebp,Suvarna1488/webm.libwebp,kleopatra999/webm.libwebp,rxl194/libwebp,PKRoma/libwebp,reimaginemedia/webm.libwebp,zofuthan/libwebp,redengineer/libwebp,imazen/libwebp,rxl194/libwebp,Maria1099/webm.libwebp,matanbs/webm.libwebp,altogother/webm.libwebp,Maria1099/webm.libwebp,altogother/webm.libwebp,ttyangf/libwebp,altogother/webm.libwebp,Aexyn/libwebp,kim42083/webm.libwebp,zofuthan/libwebp,kleopatra999/webm.libwebp,gshORTON/webm.libwebp,kim42083/webm.libwebp,jacklicn/libwebp,Distrotech/libwebp,jiehu5114/libwebp,PKRoma/libwebp,comoyo/gonzo-libwebp,cysp/libwebp,keane83/BLE_IM,comoyo/gonzo-libwebp,gshORTON/webm.libwebp,webmproject/libwebp,zofuthan/libwebp,keane83/BLE_IM,kim42083/webm.libwebp,kim42083/webm.libwebp,comoyo/gonzo-libwebp,reimaginemedia/webm.libwebp,webmproject/libwebp,ericmckean/webm.libwebp,appunite/libwebp,comoyo/gonzo-libwebp,abwiz0086/webm.libwebp,cysp/libwebp,altogother/webm.libwebp,PKRoma/libwebp,Tekserve/libwebp,Acidburn0zzz/webm.libwebp,keane83/BLE_IM,keane83/BLE_IM,kalli123/webm.libwebp,zofuthan/libwebp,iniwf/webm.libwebp,ericmckean/webm.libwebp,Suvarna1488/webm.libwebp,webmproject/libwebp,comoyo/gonzo-libwebp,ya7lelkom/libwebp,jacklicn/libwebp,cysp/libwebp,jiehu5114/libwebp,Suvarna1488/webm.libwebp,appunite/libwebp,appunite/libwebp,reimaginemedia/webm.libwebp,matanbs/webm.libwebp,kalli123/webm.libwebp,appunite/libwebp,Distrotech/libwebp,jiehu5114/libwebp,imazen/libwebp,gshORTON/webm.libwebp,Maria1099/webm.libwebp,Acidburn0zzz/webm.libwebp,ya7lelkom/libwebp,abwiz0086/webm.libwebp,appunite/libwebp,cysp/libwebp,Suvarna1488/webm.libwebp,rxl194/libwebp,Acidburn0zzz/webm.libwebp,yohunl/libwebp,dumganhar/libwebp,webmproject/libwebp,comoyo/gonzo-libwebp,iniwf/webm.libwebp,Aexyn/libwebp,imazen/libwebp,iniwf/webm.libwebp,PKRoma/libwebp,ya7lelkom/libwebp,jiehu5114/libwebp,imazen/libwebp,PKRoma/libwebp,matanbs/webm.libwebp,rxl194/libwebp,yohunl/libwebp,redengineer/libwebp,webmproject/libwebp,zofuthan/libwebp,kleopatra999/webm.libwebp,jacklicn/libwebp,ericmckean/webm.libwebp,iniwf/webm.libwebp,ya7lelkom/libwebp,rxl194/libwebp,abwiz0086/webm.libwebp,comoyo/gonzo-libwebp,Tekserve/libwebp,dumganhar/libwebp,redengineer/libwebp,Aexyn/libwebp,gshORTON/webm.libwebp,jacklicn/libwebp,ya7lelkom/libwebp,ttyangf/libwebp,Aexyn/libwebp,appunite/libwebp,ericmckean/webm.libwebp,altogother/webm.libwebp,Maria1099/webm.libwebp,ttyangf/libwebp,Tekserve/libwebp,Acidburn0zzz/webm.libwebp,dumganhar/libwebp,kalli123/webm.libwebp,Maria1099/webm.libwebp,kim42083/webm.libwebp,yohunl/libwebp,kalli123/webm.libwebp,reimaginemedia/webm.libwebp,abwiz0086/webm.libwebp,PKRoma/libwebp,reimaginemedia/webm.libwebp,Tekserve/libwebp,Suvarna1488/webm.libwebp,Aexyn/libwebp,kalli123/webm.libwebp,redengineer/libwebp,ttyangf/libwebp