Implement I_SUID/I_SGID feature for binfs in the POSIX compliant way.
If set-user-ID bit is set in the file permissions, then the effective
user ID of process shall be set to UID of the new process image file.
test case:
hello example emulates to set uid and file set-user-ID bit, and call
geteuid and getegid API.
UID = 2000
GID = 3000
MODE = 06555
nsh> ls -l /bin/hello
-r-sr-sr-x 2000 3000 0 hello
nsh> hello
geteuid:2000
getegid:3000
Signed-off-by: fangxinyong <fangxinyong@xiaomi.com>
