include vector explicitly (#2740)

Summary:
Pull Request resolved: #2740

errors out when cross compile for android

 {F1474271712}

Reviewed By: kimishpatel, JacobSzwejbka

Differential Revision: D55457736

fbshipit-source-id: 993db6006b9aa0553097428f5fec6256cb39a1aa

Author: cccclai

examples/models/llama2/custom_ops/op_sdpa.cpp

@@ -16,6 +16,7 @@
 #include <executorch/runtime/core/exec_aten/util/scalar_type_util.h>
 
 #include <array>
+#include <vector>
 
 #ifdef ET_USE_THREADPOOL
 #include <executorch/backends/xnnpack/threadpool/threadpool.h>