1.modifications:
modified:   syscall/fs_syscall.c
modified:   syscall/los_syscall.h
modified:   syscall/syscall_lookup.h
2.add 1 testcases:
modified:   testsuites/unittest/IO/BUILD.gn
modified:   testsuites/unittest/IO/full/IO_test_pselect_001.cpp
modified:   testsuites/unittest/IO/io_test.cpp
3.influence:
none

re #I45SXU
Signed-off-by: Nwangchen <253227059@qq.com>
Change-Id: I03a5d464fd5423c360e42f7d141035ce0d83d8a8