Busulfan, Fludarabine Phosphate, and Anti-Thymocyte Globulin Followed By Donor Stem Cell Transplant and Azacitidine in Treating Patients With High-Risk Myelodysplastic Syndrome and Older Patients With Acute Myeloid Leukemia

acute myeloid leukemia, adult acute megakaryoblastic leukemia, adult acute monoblastic leukemia, adult acute monocytic leukemia, adult acute myeloid leukemia with inv(16)(p13.1q22); cbfb-myh11, adult acute myeloid leukemia with maturation, adult acute myeloid leukemia with minimal differentiation, adult acute myeloid leukemia with t(16;16)(p13.1;q22); cbfb-myh11, adult acute myeloid leukemia with t(8;21); (q22; q22.1); runx1-runx1t1, adult acute myeloid leukemia with t(9;11)(p21.3;q23.3); mllt3-mll, adult acute myeloid leukemia without maturation, adult acute myelomonocytic leukemia