Coverity: mark return value as explicitly 'ignored'
Coverity: mark return value as explicitly 'ignored'

CID 981035

darktable-org/rawspeed,darktable-org/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed