thread.h: rename interface param
thread.h: rename interface param

this matches the code in thread.c; interface is a reserved word in some
windows configurations.

Change-Id: I9570b14171023214a51263211693f1a858a13acf

zofuthan/libwebp,altogother/webm.libwebp,altogother/webm.libwebp,Suvarna1488/webm.libwebp,gshORTON/webm.libwebp,Acidburn0zzz/webm.libwebp,jiehu5114/libwebp,webmproject/libwebp,iniwf/webm.libwebp,zofuthan/libwebp,matanbs/webm.libwebp,imazen/libwebp,iniwf/webm.libwebp,yohunl/libwebp,ya7lelkom/libwebp,jiehu5114/libwebp,kleopatra999/webm.libwebp,kalli123/webm.libwebp,iniwf/webm.libwebp,jacklicn/libwebp,Maria1099/webm.libwebp,altogother/webm.libwebp,imazen/libwebp,altogother/webm.libwebp,Aexyn/libwebp,jiehu5114/libwebp,Aexyn/libwebp,zofuthan/libwebp,Suvarna1488/webm.libwebp,jacklicn/libwebp,ericmckean/webm.libwebp,ya7lelkom/libwebp,reimaginemedia/webm.libwebp,imazen/libwebp,ya7lelkom/libwebp,matanbs/webm.libwebp,altogother/webm.libwebp,reimaginemedia/webm.libwebp,Acidburn0zzz/webm.libwebp,abwiz0086/webm.libwebp,jiehu5114/libwebp,zofuthan/libwebp,jacklicn/libwebp,iniwf/webm.libwebp,imazen/libwebp,kim42083/webm.libwebp,ttyangf/libwebp,abwiz0086/webm.libwebp,gshORTON/webm.libwebp,Maria1099/webm.libwebp,webmproject/libwebp,kim42083/webm.libwebp,kim42083/webm.libwebp,redengineer/libwebp,redengineer/libwebp,imazen/libwebp,Acidburn0zzz/webm.libwebp,kim42083/webm.libwebp,Suvarna1488/webm.libwebp,PKRoma/libwebp,Maria1099/webm.libwebp,Aexyn/libwebp,Acidburn0zzz/webm.libwebp,yohunl/libwebp,yohunl/libwebp,kim42083/webm.libwebp,webmproject/libwebp,gshORTON/webm.libwebp,matanbs/webm.libwebp,ericmckean/webm.libwebp,abwiz0086/webm.libwebp,ttyangf/libwebp,ttyangf/libwebp,ttyangf/libwebp,rxl194/libwebp,ya7lelkom/libwebp,abwiz0086/webm.libwebp,PKRoma/libwebp,kalli123/webm.libwebp,reimaginemedia/webm.libwebp,redengineer/libwebp,kalli123/webm.libwebp,Aexyn/libwebp,PKRoma/libwebp,PKRoma/libwebp,zofuthan/libwebp,matanbs/webm.libwebp,kleopatra999/webm.libwebp,ya7lelkom/libwebp,jiehu5114/libwebp,yohunl/libwebp,ericmckean/webm.libwebp,Acidburn0zzz/webm.libwebp,iniwf/webm.libwebp,webmproject/libwebp,abwiz0086/webm.libwebp,kalli123/webm.libwebp,ttyangf/libwebp,kleopatra999/webm.libwebp,Suvarna1488/webm.libwebp,redengineer/libwebp,rxl194/libwebp,Aexyn/libwebp,jacklicn/libwebp,redengineer/libwebp,rxl194/libwebp,kleopatra999/webm.libwebp,yohunl/libwebp,PKRoma/libwebp,PKRoma/libwebp,rxl194/libwebp,gshORTON/webm.libwebp,rxl194/libwebp,kleopatra999/webm.libwebp,webmproject/libwebp,Suvarna1488/webm.libwebp,matanbs/webm.libwebp,reimaginemedia/webm.libwebp,ericmckean/webm.libwebp,ericmckean/webm.libwebp,reimaginemedia/webm.libwebp,gshORTON/webm.libwebp,jacklicn/libwebp,kalli123/webm.libwebp,Maria1099/webm.libwebp,Maria1099/webm.libwebp