tests/uid*: use fchown* instead of chown*

Newer architectures have no chown syscall, so use fchown* syscalls
for testing printuid.

* tests/uid.test: Use fchown instead of chown.
* tests/uid.c: Test __NR_fchown instead of __NR_chown.
(main): Use __NR_fchown instead of __NR_chown.
* tests/uid32.c: Test __NR_fchown32 instead of __NR_chown32.
(main): Use __NR_fchown32 instead of __NR_chown32.
* tests/uid16.c: Test __NR_fchown and __NR_fchown32 instead
of __NR_chown and __NR_chown32.
(main): Use __NR_fchown instead of __NR_chown.
* tests/uid.awk: Update regexp.
5 files changed