raspistill: Fix not copying the terminating byte of filename
raspistill: Fix not copying the terminating byte of filename

raspberrypi/userland,raspberrypi/userland,StealthMicro/userland,erlerobot/rpi-userland,JamesH65/userland,d3faultdotxbe/raspivid-accurate-fps-via-hacky-framedropping,popcornmix/userland,kraj/userland,FIIT-TNL/userland,6by9/userland,popcornmix/userland,maxnet/userland,d3faultdotxbe/raspivid-accurate-fps-via-hacky-framedropping,raspberrypi/userland,DexterInd/userland,roberttidey/userland,maroviher/userland,fredericofs/userland,ethanol100/userland,luked99/userland-1,gonzoua/userland,oniongarlic/userland,popcornmix/userland,adamheinrich/userland,ethanol100/userland,d3faultdotxbe/raspivid-accurate-fps-via-hacky-framedropping,oniongarlic/userland,erlerobot/rpi-userland,adamheinrich/userland,StealthMicro/userland,kraj/userland,ethanol100/userland,maroviher/userland,FIIT-TNL/userland,roberttidey/userland,hyunkim9123/userland,hyunkim9123/userland,oniongarlic/userland,adamheinrich/userland,DexterInd/userland,kraj/userland,d3faultdotxbe/raspivid-accurate-fps-via-hacky-framedropping,luked99/userland-1,yzhahn/userland,salih/userland,salih/userland,hyunkim9123/userland,FIIT-TNL/userland,maroviher/userland,luked99/userland-1,gonzoua/userland,JamesH65/userland,yzhahn/userland,fredericofs/userland,maxnet/userland,StealthMicro/userland,maxnet/userland,DexterInd/userland,6by9/userland,roberttidey/userland,JamesH65/userland,yzhahn/userland,erlerobot/rpi-userland,fredericofs/userland,6by9/userland,salih/userland,gonzoua/userland