Fixed compile error with GCC/clang.
Fixed compile error with GCC/clang.

neilmacintosh/GSL,AraszDev/GSL,r0mai/GSL,igetgames/GSL,kylog/GSL,mazalet/GSL,eteran/GSL,zbelial/GSL,nguarracino/GSL,martinmoene/GSL,Josaphat/GSL,dacap/GSL,subailong/GSL,PSPDFKit-labs/GSL,bashrc-real/GSL,vladon/GSL,kevgs/GSL,s8435330song/GSL,BeiLuoShiMen/GSL,socantre/GSL,kernhanda/GSL,rexkerr/GSL,john-lynch/GSL,allsea9/GSL,trebconnell/GSL,garyfurnish/GSL,shaunstanislaus/GSL,jbcoe/GSL,tamaskenez/GSL,matus-chochlik/GSL