add missing declarations for slice C-API
add missing declarations for slice C-API

ChristopherHogan/cython,c-blake/cython,ChristopherHogan/cython,JelleZijlstra/cython,mcanthony/cython,andreasvc/cython,acrispin/cython,fperez/cython,roxyboy/cython,ABcDexter/cython,JelleZijlstra/cython,da-woods/cython,cython/cython,marscher/cython,mrGeen/cython,hhsprings/cython,andreasvc/cython,hickford/cython,slonik-az/cython,fperez/cython,hhsprings/cython,c-blake/cython,mcanthony/cython,JelleZijlstra/cython,marscher/cython,mcanthony/cython,scoder/cython,encukou/cython,dahebolangkuan/cython,achernet/cython,marscher/cython,hickford/cython,fabianrost84/cython,acrispin/cython,JelleZijlstra/cython,roxyboy/cython,c-blake/cython,hickford/cython,madjar/cython,scoder/cython,acrispin/cython,cython/cython,andreasvc/cython,da-woods/cython,encukou/cython,fperez/cython,roxyboy/cython,cython/cython,da-woods/cython,madjar/cython,fabianrost84/cython,madjar/cython,slonik-az/cython,acrispin/cython,madjar/cython,hhsprings/cython,madjar/cython,fabianrost84/cython,ABcDexter/cython,ChristopherHogan/cython,roxyboy/cython,ABcDexter/cython,da-woods/cython,andreasvc/cython,c-blake/cython,acrispin/cython,scoder/cython,roxyboy/cython,achernet/cython,achernet/cython,achernet/cython,dahebolangkuan/cython,slonik-az/cython,fabianrost84/cython,dahebolangkuan/cython,cython/cython,JelleZijlstra/cython,hhsprings/cython,fperez/cython,mrGeen/cython,c-blake/cython,encukou/cython,mcanthony/cython,hickford/cython,slonik-az/cython,encukou/cython,dahebolangkuan/cython,encukou/cython,andreasvc/cython,mcanthony/cython,hickford/cython,slonik-az/cython,ABcDexter/cython,dahebolangkuan/cython,marscher/cython,ABcDexter/cython,mrGeen/cython,mrGeen/cython,mrGeen/cython,fabianrost84/cython,marscher/cython,fperez/cython,achernet/cython,hhsprings/cython,scoder/cython