Protect entry_point and image_path from NULL
Protect entry_point and image_path from NULL

Libsass crashes if implementer does not set a default
option for image_path. Protect the sass_interface the
same way as SassC does.

technoAri/libsass,TBAPI-0KA/NSass,saper/libsass,errorx666/libsass,webdev1001/libsass,am11/libsass,moovweb/libsass,mikebarkas/libsass,saper/libsass,khchanel/libsass,mikebarkas/libsass,moovweb/libsass,admire93/libsass-python,mtwebster/mint-libsass,webdev1001/libsass,TBAPI-0KA/NSass,mtwebster/mint-libsass,technoAri/libsass,khchanel/libsass,webdev1001/libsass,am11/libsass,FishingCactus/libsass,technoAri/libsass,FishingCactus/libsass,TBAPI-0KA/NSass,panicinc/libsass,khchanel/libsass,panicinc/libsass,dahlia/libsass-python,errorx666/libsass,am11/libsass,moovweb/libsass,mikebarkas/libsass,webdev1001/libsass,mikebarkas/libsass,TBAPI-0KA/NSass,am11/libsass,FishingCactus/libsass,mikebarkas/libsass,dahlia/libsass-python,panicinc/libsass,mtwebster/mint-libsass,TBAPI-0KA/NSass,saper/libsass,khchanel/libsass,panicinc/libsass,technoAri/libsass,errorx666/libsass,khchanel/libsass,technoAri/libsass,webdev1001/libsass,saper/libsass,saper/libsass,moovweb/libsass,admire93/libsass-python,TBAPI-0KA/NSass,mtwebster/mint-libsass,panicinc/libsass,FishingCactus/libsass,errorx666/libsass,mtwebster/mint-libsass,FishingCactus/libsass,am11/libsass