1.modifications:
modified:   syscall/los_syscall.h
modified:   syscall/misc_syscall.c
modified:   syscall/syscall_lookup.h
2.add 3 testcases:
testsuites/unittest/IO/full/IO_test_ppoll_001.cpp
testsuites/unittest/IO/full/IO_test_ppoll_002.cpp
3.influence:
none
Signed-off-by: Nteamol <28105285@qq.com>

Change-Id: I885610a62b980bd3720b337aced886450338bdcf

Change-Id: I7f4add72f2fd1cc3770bcf103d1909add4829822

Change-Id: Ice1193d1ae7f2e0d12a2a38a306a6399407f5037