fix two minor memory leaks in webpmux
fix two minor memory leaks in webpmux

(only occur in case of error)

Change-Id: Icab69bb364b77f8eae6cae91047354c27e610602
(cherry picked from commit 3e59a74d721ed15c8845c9c1215dcb09fdb55fa6)

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