Use isl_stat as return value for isl_val_get_num_isl_int
This function was overlooked in
370a8b7d (introduce isl_bool and
isl_stat return types, Mon May 4 09:45:16 2015 +0200). By making
isl_val_get_num_isl_int return an isl_stat, implicit int to enum
conversions in isl_coalesce.c:shift_if_cst_int are avoided, which
triggered static analysis warnings due to the converted int potentially
being beyond the range of the isl_enum.
Signed-off-by: Tobias Grosser <tobias@grosser.es>
Signed-off-by: Sven Verdoolaege <sven.verdoolaege@gmail.com>