Fix RGXImage::saveBitmap on empty string input
Fix RGXImage::saveBitmap on empty string input

segs.size() - 1 could underflow, also solves signed/unsigned comparison
warning

FranciscoDA/OpenApoc,AndO3131/OpenApoc,pmprog/OpenApoc,FranciscoDA/OpenApoc,steveschnepp/OpenApoc,pmprog/OpenApoc,AndO3131/OpenApoc,ShadowDancer/OpenApoc,Istrebitel/OpenApoc,Istrebitel/OpenApoc,ShadowDancer/OpenApoc,FranciscoDA/OpenApoc,steveschnepp/OpenApoc,AndO3131/OpenApoc