merge r8978: only require popt if it really is mandatory
merge r8978: only require popt if it really is mandatory

git-svn-id: 84309296e5159d32aabeca12da51dba852c01f50@8981 67ed7778-7388-44ab-90cf-0a291f65f57c

gphoto/libgphoto2-python,gphoto/libgphoto2.OLDMIGRATION,gphoto/libgphoto2.OLDMIGRATION,gphoto/libgphoto2-sharp,gphoto/libgphoto2-sharp,gphoto/libgphoto2.OLDMIGRATION,gphoto/libgphoto2.OLDMIGRATION