isl_ast_build_expr.c: isl_ast_expr_add_term: store local space in data structure
isl_ast_build_expr.c: isl_ast_expr_add_term: store local space in data structure

isl_ast_expr_add_term is already passed a data structure
with information that is reused over multiple calls,
so it might as well also store the domain local space
of the original affine expression.

Signed-off-by: Sven Verdoolaege <dd860110a62b19214c4ee03aec0abffecb4e86b8@cerebras.net>

Meinersbur/isl,Meinersbur/isl,Meinersbur/isl,Meinersbur/isl