tftp-hpa: fix build with newer gcc
tftp-hpa: fix build with newer gcc

mati865/MSYS2-packages,mati865/MSYS2-packages,mati865/MSYS2-packages,JPeterMugaas/MSYS2-packages,waterlan/MSYS2-packages,mati865/MSYS2-packages,JPeterMugaas/MSYS2-packages,waterlan/MSYS2-packages,JPeterMugaas/MSYS2-packages,waterlan/MSYS2-packages,JPeterMugaas/MSYS2-packages,waterlan/MSYS2-packages