Fix return types for SV getters.
Fix return types for SV getters.

vickenty/loljit,vickenty/loljit,vickenty/loljit,vickenty/loljit,vickenty/libjit-perl,vickenty/libjit-perl,vickenty/libjit-perl,vickenty/libjit-perl,vickenty/libjit-perl