fix memory leak in assignment

Author: Joe Petviashvili

src/indexing.jl

@@ -49,6 +49,7 @@ end
 function assign_gen!(lhs::AFArray,ndims::dim_t,indices,rhs::AFArray)
     out = RefValue{af_array}(lhs.arr)
     _error(ccall((:af_assign_gen,af_lib),af_err,(Ptr{af_array},af_array,dim_t,Ptr{af_index_t},af_array),out,lhs.arr,ndims,indices,rhs.arr))
+    release_array(lhs)
     lhs.arr = out[]
 end